compilation -> compression [ci skip]

[ci skip] Clarify that the minimum version of a "gem" is bumped

The previous sentence does not convey whether the minimum version of SQLite3 is bumped or the minimum version of `sqlite3` gem is bumped.

[ci skip] Typo: Javascript -> JavaScript

[ci skip] Fix grammar

[ci skip] mysql -> MySQL

[ci skip] ActionView -> Action View

[ci skip] Mime -> MIME

[ci skip] Expand JS to JavaScript for clarity

[skip ci] arel -> Arel

[ci skip] Typo: ActiveSuppport -> ActiveSupport

As per the documentation guides, we write `Arel` instead of `arel`.

The correct word is `MIME` which is an acronym which stands for `Multipurpose Internet Mail Extensions`.

Reference: https://en.wikipedia.org/wiki/MIME

As per the documentation guides, we use 'Action View' instead of `ActionView` in the general language.

Reference: https://github.com/rails/rails/commit/27138386ad8dbda2eb44e622515626f352fd3b22

##### Singular

`route exists`

##### Plural

`routes exist`

[ci skip] Fix confusing sentence in upgrade guide

[ci skip] Corrected the sentence in upgrade guide 

Closes #28707.

Introduce ActiveSupport::Notifications.monotonic_subscribe

Introduce 'ActiveSupport::Notifications::Fanout::Subscribers::MonotonicTimed' and 'ActiveSupport::Notifications::monotonic_subscribe'

Also, change the signature of ‘ActiveSupport::Notifications::Fanout#subscribe’ to accept optional ‘monotonic’ boolean argument. Then initialize either a ‘Timed’ or ‘MonotonicTimed’ subscriber based on the value of ‘monotonic’ parameter.

Introduce ‘ActiveSupport::Notifications::monotonic_subscribe’ method

Also, provision ‘ActiveSupport::Notifications::subscribed’ to optionally accept ‘monotonic’ boolean argument.

Update documentation for ActiveSupport::Notifications

Add tests

Update guides documentation under the 'Active Support Instrumentation' chapter

Incorporate feedback: use optional keyword argument to specify optional 'monotonic' option to 'subscribed' method

Fix a typo

Expose `mailbox_for` method

Use a better requirement for sass-rails 6 prereleases

Fix indentation of the config.eager_load nil warning

This is the behavior I naively expect for the operator when used with a
single digit, but it's definitely an edge case for it, and it doesn't
seem to work as expected for including prereleases.

Using >= works fine and make the intention more clear anyways.

bundle update resque-scheduler to latest version

Only build middleware proxy when instrumentating

The instrumentation proxy adds three stack frames per-middleware, even
when nothing is listening.

This commit, when the middleware stack is built, only adds
instrumentation when the `process_middleware.action_dispatch` event has
already been subscribed to.

The advantage to this is that we don't have any extra stack frames in
apps which don't need middleware instrumentation.

The disadvantage is that the subscriptions need to be in place when the
middleware stack is built (during app boot). I think this is likely okay
because temporary AS::Notifications subscriptions are strongly
discouraged.

Fix indentation for config.eager_load nil warning message