Update `rails server` terminal output in Guides [ci skip]

Merge pull request #37353 from lxxxvi/correct-information-about-record-identification-for-form-helper

correct information about record identification in form helper [ci skip]

Corrected config option path in release notes for deprecation release notes of Rails 6 [ci skip]

[ci skip] Note removal of `render :text` & `:nothing` options from 5.1 upgrade guide

This is the conventional name for that parameter.

Fix code block in the HTML version of the upgrade guide

[ci skip]

Document the new npm package names in the upgrade guide

Clarify severe security issues maintenance policy [ci skip]

Change the Rails gem version from 6.0.0.rc1 to 6.0.0 in bug report templates

[Rafael Mendonça França + bogdanvlviv]

Fix Rails Version in Guides Index

Only Rails 6.0 and 5.2 are supported now.

Talk about the thread-safe concerns of the classic autoloader in
development.

This 6.x seems to be confusing to some people.

Fixed cache_store name used in adding other modules section of api app documentation guide. [ci skip]

Added multiple database Active Record guide entry to the release notes

Added missing comment notation for the example of form_with in form_helpers.md documentation. [ci skip]

Added missing changelog entry for new guide added for Multiple Databases with Active Record(#36389) [ci skip]

Documentation for ActionMailer's SMTP over SSL/TLS option

[ci skip]

Use a single term instead of all terms used to describe path and URL helpers together

[ci skip] add CSRF token explanation for javascript documentation

fix a typo in 5_2_release_notes.md

Fix cache_timestamp_format default value in guides

Assigning to a collection of attachments appends rather than replacing, as in 5.2. Existing 5.2 apps that rely on this behavior will no longer break when they're upgraded to 6.0.

For apps generated on 6.0 or newer, assigning replaces the existing attachments in the collection. #attach should be used to add new attachments to the collection without removing existing ones.

I expect that we'll deprecate the old behavior in 6.1.

Closes #36374.