Update all links in root README.md with January 2020 release tags

[joshfree]

Tracking issue to update all links embedded in the root repo README.md next week after release tags have been created.

Related: #7098

/cc @hemanttanwar @JimSuplizio

[hemanttanwar]

I spoke to @weshaggard and he suggested not to keep embedded links to libraries in this root README. Instead of link to Appropriate release.
https://azure.github.io/azure-sdk/releases/2020-01/java.html
It avoids replication of links and reduce chance of error in future.
I will do it after azure-core release.

[hemanttanwar]

PR #7236

[hemanttanwar]

The PR is closed, sdk/README.md links for SDK should be resolved now.