Fix DocBlocks for duplicate hooks

[keesiemeijer]

DocBlocks should start with /** to be recognized as a DocBlock by the ​phpdoc-parser. Duplicate undocumented hooks are imported if normal comments (/* */) are used.

These hooks don't have a correct DocBlock.

• load-widgets.php
• widgets.php
• sidebar_admin_setup
• comment_email
• session_token_manager
• rest_insert_attachment
• rest_insert_comment
• rest_insert_{$this->post_type}
• rest_insert_{$this->taxonomy}
• rest_insert_user

[keesiemeijer]

Fix DocBlocks for duplicate hooks

[netweb]

We should add something to the handbook here documenting this:

​https://make.wordpress.org/core/handbook/best-practices/inline-documentation-standards/php/#4-hooks-actions-and-filters

[keesiemeijer]

I just found out the hooks are in fact, not imported when a DocBlock isn't found by the parser. But we should adhere to the DocBlock syntax /** where possible.

There is a ​note for multi-line comments in the handbook documenting this.

[SergeyBiryukov]

In 39668:

Docs: Add missing duplicate hook references in wp-admin/includes/ajax-actions.php.

Props keesiemeijer.
See #39371.

[SergeyBiryukov]

In 39669:

Docs: Correct comment_email duplicate hook reference in wp-admin/includes/class-wp-comments-list-table.php.

Props keesiemeijer.
See #39371.

[SergeyBiryukov]

In 39670:

Docs: Add missing session_token_manager duplicate hook reference in wp-includes/class-wp-session-tokens.php.

Props keesiemeijer.
See #39371.

[SergeyBiryukov]

In 39671:

Docs: Correct rest_insert_* duplicate hook references in REST API.

Props keesiemeijer.
Fixes #39371.