Also improves docs for `Time#find_zone!`

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Stems from comments by @zzak on e07f3ddc:

* https://github.com/rails/docrails/commit/e07f3ddcac394d2a8dc23fc571318b7e8c2497b1#commitcomment-9015634
* https://github.com/rails/docrails/commit/e07f3ddcac394d2a8dc23fc571318b7e8c2497b1#commitcomment-9015639

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Fix Duplicate web-console entries in Gemfile

Fix minor typos in autoloading guide [ci skip]

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/cc @fxn

/cc @fxn

Add `null` option to timestamps as migration generator does [ci skip]

Re-enable capture'ing non-String values

This has been discussed in #17661 and partially reverts the changes made
in 9de83050 and 986cac73

The test case added to content_for acts as a regression / acceptance test.

Allow URL helpers to work with optional scopes

ParameterFilter shouldn't try to dup symbol keys

Pass connection rather than alias_tracker

Fix handling of positional url helper arguments when format is false

There is no need to subtract one from the path_params size when there is
no format parameter because it is not present in the path_params array.

Fixes #17819.

Because we're only using the `connection` so passing the entire tracker
isn't unnecessary.

Eventually only the `connection` will be passed to `add_constraints`
with later refactoring but curretly that's not possible because of
`construct_tables` method.

[guides] Fix method name inconsistency in a mailer example

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