Doc: Update shortcut list in the FAQ section

[t-hamano]

What?

This PR updates the shortcut list in the FAQ section as the keyboard shortcut modal in the block editor appears.

This PR includes the following changes:

• Update shortcut descriptions
• Change section title (Editor shortcuts > Global shortcut)
• Merge alternative shortcuts into one line
• Reordering
• Add missing shortucts:
  • Toggle distraction free mode.
  • Insert a link to a post or page.
  • Convert the current heading to a paragraph.
  • Convert the current paragraph or heading to a heading of level 1 to 6."

Testing Instructions

• See the FAQ section of this branch.
• Open the keyboard shortcut modal in the block editor and confirm that it matches the content of the document.

Note: There are slight differences in the order of keyboard shortcuts and the number of items in each editor. This PR prioritizes matching the keyboard shortcuts to the post editor.

---

Update: I've updated this PR to resolve the conflict and base it on the latest keyboard shortcut modal. Below is a list of shortcuts that appear in each editor's keyboard shortcuts modal.

Common

Shortcut	Post Editor	Site Editor	Widget Editor	Customize Widget
Display these keyboard shortcuts.	〇	〇	〇	〇

Global Shortcuts

Shortcut	Post Editor	Site Editor	Widget Editor	Customize Widget
Navigate to the nearest toolbar.	〇	〇	〇	〇
Open the command palette.	〇	〇
Switch between visual editor and code editor.	〇	〇
Toggle distraction free mode.	〇	〇
Toggle fullscreen mode.	〇
Open the block list view.	〇	〇
Show or hide the Settings sidebar.	〇	〇
Navigate to the next part of the editor.	〇	〇	〇
Navigate to the previous part of the editor.	〇	〇	〇
Save your changes.	〇	〇	〇	〇
Undo your last changes.	〇	〇	〇	〇
Redo your last undo.	〇	〇	〇	〇

Selection Shortcuts

Shortcut	Post Editor	Site Editor	Widget Editor	Customize Widget
Select all text when typing. Press again to select all blocks.	〇	〇	〇	〇
Clear selection.	〇	〇	〇	〇
Select text across multiple blocks.	〇	〇	〇	〇

Block Shortcuts

Shortcut	Post Editor	Site Editor	Widget Editor	Customize Widget
Duplicate the selected block(s).	〇	〇	〇	〇
Remove the selected block(s).	〇	〇	〇	〇
Insert a new block before the selected block(s).	〇	〇	〇	〇
Insert a new block after the selected block(s).	〇	〇	〇	〇
Delete selection.	〇	〇	〇	〇
Move the selected block(s) up.	〇	〇	〇	〇
Move the selected block(s) down.	〇	〇	〇	〇
Change the block type after adding a new paragraph.	〇	〇	〇	〇

Text formatting

Shortcut	Post Editor	Site Editor	Widget Editor	Customize Widget
Make the selected text bold.	〇	〇	〇	〇
Make the selected text italic.	〇	〇	〇	〇
Convert the selected text into a link.	〇	〇	〇	〇
Remove a link.	〇	〇	〇	〇
Insert a link to a post or page.	〇	〇	〇	〇
Underline the selected text.	〇	〇	〇	〇
Strikethrough the selected text.	〇	〇	〇	〇
Make the selected text inline code.	〇	〇	〇	〇
Convert the current heading to a paragraph.	〇	〇	〇	〇
Convert the current paragraph or heading to a heading of level 1 to 6.	〇	〇	〇	〇

[t-hamano]

Based on this comment, I will close this PR.