Include CHANGELOG.md in published releases again

[octogonz]

Sometime in March 2022, the CHANGELOG.md file stopped being included in any NPM packages released by Rush Stack.

It was caused by a PNPM upgrade at some point, reflecting a decision made by NPM v7.12.0:

PR npm/cli#3200

• 99ff40dff npm-packlist@2.2.0:
  • feat(npmignore): Do not force include history, changelogs, notice

The fix

Update the .npmignore template for all projects to explicitly include CHANGELOG.md. I've also included CHANGELOG.json since it was included before and might be useful.

CC @chengcyber

[octogonz]

Corresponding TSDoc PR: microsoft/tsdoc#420

[octogonz]

Methodology in case we need it again:

1. Delete the comment that was outside the template block

Search and delete: # (Add your project-specific overrides here)

2. Delete patterns moved to the template

Search and delete: !heft-plugin.json and !rush-plugin-manifest.json

3. Update the template:

Search for: ([\r\n]|.)+LINE[\r\n\s]+#[- ]+

Replace with:

# THIS IS A STANDARD TEMPLATE FOR .npmignore FILES IN THIS REPO.

# Ignore all files by default, to avoid accidentally publishing unintended files.
*

# Use negative patterns to bring back the specific things we want to publish.
!/bin/**
!/lib/**
!/lib-*/**
!/dist/**

!CHANGELOG.md
!CHANGELOG.json
!heft-plugin.json
!rush-plugin-manifest.json
!ThirdPartyNotice.txt

# Ignore certain patterns that should not get published.
/dist/*.stats.*
/lib/**/test/
/lib-*/**/test/
*.test.js

# NOTE: These don't need to be specified, because NPM includes them automatically.
#
# package.json
# README.md
# LICENSE

# ---------------------------------------------------------------------------
# DO NOT MODIFY ABOVE THIS LINE!  Add any project-specific overrides below.
# ---------------------------------------------------------------------------

4. Remove blank lines introduced by deletion

Search for \r?\n\r?\n\r?\n\r?
Replace with \n