Merge branch 'deprecate_numeric_since_ago' of https://github.com/chancancode/rails

Conflicts:
	activesupport/CHANGELOG.md
[ci skip] removed singulars section from classify doc
Fix on-site markdown rendering [ci skip]
Merge pull request #13079 from gregmolnar/inflector_docs

[ci skip] removed singulars section from classify doc
Deprecate ActiveSupport::TestCase.describe

Provide message to define ActiveSupport::TestCase.name instead.
Allow calling describe with a block, which Minitest::Spec does.
Merge pull request #13082 from blowmage/deprecate_describe

Deprecate ActiveSupport::TestCase.describe
fixed typo `destory` => `destroy` [ci skip]
fixed-case when invalid action name has passed
Merge pull request #13083 from kuldeepaggarwal/typos

fixed typo `destory` => `destroy` [ci skip]
Merge pull request #13054 from senny/remove_oracle_tests

Remove leftover Oracle tests.
Do not create synonym named subjects
because it is only used in
`activerecord/test/cases/adapters/oracle/synonym_test.rb`

See rails/rails#13054
remove duplicate sentence from AS changelog. [ci skip].
move "HTTP PATCH" paragraph into "Upgrading 3.2 -> 4.0". [ci skip]
3.2 to 4.0 section in upgrading guide is no longer wip. [ci skip]
create 4.1 release notes guide scaffold. [ci skip]
first pass through CHANGELOGS to extract 4_1_release_notes. [ci skip]

Extract **notable changes**, **deprecations** and **removals** from
each CHANGELOG.

I tried to reference the commits and pull requests for new features
and deprecations.

In the process I also made some minor changes to the CHANGELOGS.

The 4_1_release_notes guide is declared WIP.
delete obsolete KINDLE.md. Closes #13037. [ci skip].
no need to explain bundler and rails new in the release notes. [ci skip]

/cc @fxn
wrap test that changes inflections in with_dup
implement rename_index natively for MySQL > 5.7