feat(user-manual): Add docs for mail snippets

[hamza221]

☑️ Resolves

• part of #10113

🖼️ Screenshots

[rakekniven]

Admin -Administration

[rakekniven]

snippets -> Snippets

[nimishavijay]

• Snippets --> Text blocks
• Move the section in the settings to below General

Inside setting dialog

• Snippets heading --> list of snippets --> Create new snippet button
• For each snippet use NcListItem component with title in one line and content in subline and 3 dot menu
• Add shared icon to the left of 3 dot menu
• In 3 dot menu delete at the end
• In 3 dot menu For edit use pencil icon
• Nice-to-have: show share icon if it's shared with other people

• new snippet dialog and edit snippet dialog --> add border in content so that it looks like a text field
  • Buttons in new and edit dialog
  • "Ok" --> "Save text block"
  • Cancel icon --> x symbol
  • Cancel button tertiary
  • width of the buttons should be fit-content
  • all buttons right aligned
• Edit dialog
  • width same as new snippet dialog
  • remove "Content" heading
  • "Shares" --> h3
  • Add placeholder in dropdown "Search for users or groups"
  • Instead of UserBubble component for added users use NcListItem (similar to calendar sharing or files sharing) with an x to remove

Incoming shared text blocks

• Allow opening and viewing full text block
• Hide section if empty

While inserting in composer

• character?
• in 3 dot menu have "Insert text block" item after smart picker item
• Open modal with list of text blocks and search bar which filters the results similar to Talk create conversation add participants modal

Follow up

• combine with smart picker