Remove techotopia, linuxtopia resources (EbookFoundation#6544)

Author: 2kindsofcs

books/free-programming-books-langs.md

@@ -398,7 +398,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [10 PRINT CHR$(205.5+RND(1)); : GOTO 10](http://10print.org) - Nick Montfort, Patsy Baudoin, John Bell, Ian Bogost, Jeremy Douglass, Mark C. Marino, Michael Mateas, Casey Reas, Mark Sample, Noah Vawter
 * [A beginner's guide to Gambas](http://distro.ibiblio.org/vectorlinux/Uelsk8s/GAMBAS/gambas-beginner-guide.pdf) - John W. Rittinghouse (PDF)
 * [Pick/Basic: A Programmer's Guide](http://www.jes.com/pb/) - Jonathan E. Sisk
-* [Visual Basic Essentials](http://www.techotopia.com/index.php/Visual_Basic_Essentials)
 
 
 ### BeanShell
@@ -461,7 +460,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 
 ### C Sharp
 
-* [C# Essentials](http://www.techotopia.com/index.php/C_Sharp_Essentials)
 * [C# Notes for Professionals](http://goalkicker.com/CSharpBook/) - Compiled from StackOverflow documentation (PDF)
 * [C# Programming](https://en.wikibooks.org/wiki/C_Sharp_Programming) - Wikibooks
 * [C# Programming Yellow Book](https://www.robmiles.com/s/CSharp-Book-2019-Refresh.pdf) - Rob Miles (PDF) (2019)
@@ -972,7 +970,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 ### iOS
 
 * [Cocoa Dev Central](http://cocoadevcentral.com)
-* [iOS 8 App Development Essentials](http://www.techotopia.com/index.php/IOS_8_App_Development_Essentials)
 * [iOS Developer Notes for Professionals](https://goalkicker.com/iOSBook/) - Compiled from StackOverflow Documentation (PDF)
 * [iOS Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/ios) (PDF, Kindle) (email address *requested*, not required)
 * [NSHipster](http://nshipster.com/#archive) (Resource)
@@ -1411,13 +1408,11 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Automated Linux From Scratch](http://www.linuxfromscratch.org/alfs/download.html)
 * [Getting Started with Ubuntu](http://ubuntu-manual.org)
 * [GNU Autoconf, Automake and Libtool](http://www.sourceware.org/autobook/download.html)
-* [GTK+/Gnome Application Development](http://www.linuxtopia.org/online_books/gui_toolkit_guides/gtk+_gnome_application_development/)
 * [Hardened Linux From Scratch](http://www.linuxfromscratch.org/hlfs/download.html)
 * [Kali Linux 2018: Assuring Security by Penetration Testing, Fourth Edition](https://www.packtpub.com/free-ebooks/kali-linux-2018-assuring-security-penetration-testing-fourth-edition) - Shiva V. N Parasram, Alex Samm, Damian Boodoo, Gerard Johansen, Lee Allen, Tedi Heriyanto, Shakeel Ali (Packt account *required*)
 * [Kali Linux: Professional Penetration-Testing Distribution](http://docs.kali.org)
 * [Learning Debian GNU/Linux](http://www.oreilly.com/openbook/debian/book/index.html)
 * [Linux 101 Hacks](http://thegeekstuff.s3.amazonaws.com/files/linux-101-hacks.zip) - Ramesh Natarajan (PDF)
-* [Linux Administrator's Security Guide](http://www.linuxtopia.org/online_books/linux_administrators_security_guide/index.html)
 * [Linux Advanced Routing & Traffic Control HOWTO](http://lartc.org)
 * [Linux Appliance Design: A Hands-On Guide to Building Linux Appliances](http://librta.org/book.html) - Bob Smith, John Hardin, Graham Phillips, Bill Pierce (PDF, EPUB, MOBI)
 * [Linux commands Notes for Professionals](https://goalkicker.com/LinuxBook/) - Compiled from StackOverflow documentation (PDF)
@@ -1427,9 +1422,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Linux Inside](https://0xax.gitbooks.io/linux-insides/content/index.html)
 * [Linux Kernel in a Nutshell](http://www.kroah.com/lkn/)
 * [Linux Newbie Administrator Guide](http://lnag.sourceforge.net)
-* [Linux Security for Beginners](http://www.linuxtopia.org/LinuxSecurity/index.html)
 * [Linux Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/linux) (PDF, Kindle) (email address *requested*, not required)
-* [Red Hat Enterprise Linux 6 Essentials](http://www.techotopia.com/index.php/Red_Hat_Enterprise_Linux_6_Essentials)
 * [Secure Programming HOWTO - Creating Secure Software](http://www.dwheeler.com/secure-programs/) - D. A. Wheeler (HTML, PDF)
 * [Ten Steps to Linux Survival: Bash for Windows People](http://dullroar.com/book/TenStepsToLinuxSurvival.html) - Jim Lehmer
 * [The Debian Administrator's Handbook](https://debian-handbook.info)
@@ -1560,7 +1553,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 ### MySQL
 
 * [MySQL 8.0 Tutorial Excerpt](https://dev.mysql.com/doc/mysql-tutorial-excerpt/8.0/en/tutorial.html) (HTML) [(PDF)](https://downloads.mysql.com/docs/mysql-tutorial-excerpt-8.0-en.pdf)
-* [MySQL Essentials](http://www.techotopia.com/index.php/MySQL_Essentials)
 * [MySQL Notes for Professionals](https://goalkicker.com/MySQLBook/) - Compiled from StackOverflow Documentation (PDF)
 
 
@@ -2090,14 +2082,12 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Practicing Ruby](https://github.com/elm-city-craftworks/practicing-ruby-manuscripts)
 * [Programming Ruby](http://ruby-doc.com/docs/ProgrammingRuby/)
 * [Ruby Best Practices](https://github.com/practicingruby/rbp-book/tree/gh-pages/pdfs) - Gregory Brown (PDF)
-* [Ruby Essentials](http://www.techotopia.com/index.php/Ruby_Essentials)
 * [Ruby Hacking Guide](http://ruby-hacking-guide.github.io)
 * [Ruby in Twenty Minutes](https://www.ruby-lang.org/en/documentation/quickstart/)
 * [Ruby Koans](http://www.rubykoans.com)
 * [Ruby Learning](http://rubylearning.com)
 * [Ruby Notes for Professionals](https://goalkicker.com/RubyBook/) - Compiled from StackOverflow Documentation (PDF)
 * [Ruby one-liners cookbook](https://learnbyexample.github.io/learn_ruby_oneliners/) - Sundeep Agarwal
-* [Ruby Programming](http://www.linuxtopia.org/online_books/programming_books/ruby_tutorial/)
 * [Ruby Style Guide](https://github.com/airbnb/ruby) - Airbnb
 * [Ruby User's Guide](https://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/index.html)
 * [Ruby Web Dev: The Other Way](https://leanpub.com/rwdtow/read) - Yevhen Kuzminov
@@ -2453,7 +2443,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 ### Visual Basic
 
 * [Visual Basic .NET Notes for Professionals](https://goalkicker.com/VisualBasic_NETBook/) - Compiled from StackOverflow Documentation (PDF)
-* [Visual Basic Essentials](http://www.techotopia.com/index.php/Visual_Basic_Essentials)
 * [Visual Basic Official Docs](https://docs.microsoft.com/en-us/dotnet/visual-basic)