Fixed README link in API [ci skip]

This should not be a link because
it's creating a link with activesupport README right now
bcrypt-ruby stable is 3.1
Merge pull request #11469 from bvogel/master

Update bcrypt-ruby stable version to 3.1
fixes plugin test for tutorial

[ci skip]
Merge pull request #11478 from newton10471/master

fixes plugin test for tutorial [ci skip]
Improve ActiveRecord::QueryMethods#includes docs

It's not immediately clear whether you can pass in multiple relations or
not. After going through the code a bit, I saw that the arguments are
just appended to an array. Also, added nested relations example.

[ci skip]
Merge pull request #11479 from henrikhodne/improve-ar-querymethods-includes-docs

Improve ActiveRecord::QueryMethods#includes docs [ci skip]
grammar fix in upgrade documentation
Merge pull request #11465 from arunagw/removed_missleading_readme_link_doc

Fixed README link in API
Use latest mysql2.

Fixes #11457
Merge pull request #11485 from simi/mysql2

Use latest mysql2.
Merge pull request #11483 from garysweaver/grammar_fix_in_upgrade_documentation

grammar fix in upgrade documentation