documentation

Pull request #3263: feature/ZBXNEXT-10141-7.5-D-v3

Merge in WEB/documentation from feature/ZBXNEXT-10141-7.5-D-v3 to release/8.0

* commit 'ab2348243f3f8d9d6c29e94636132abd4717e283':
  [ZBXNEXT-10141] restored images
  [ZBXNEXT-10141] updated wording & formatting based on PR suggestions
  [ZBXNEXT-10141] added, removed, updated image sizes
  [ZBXNEXT-10141] updated wording & formatting based on PR suggestions
  [ZBXNEXT-10141] *Time period* selector → time period selector & *Host* selector → host selector & related changes
  [ZBXNEXT-10141] added link to "Dashboard widget parameters" for quick access; added minor format changes
  [ZBXNEXT-10141] added "Dashboard widgets" overview page and updated widget overviews
  [ZBXNEXT-10141] restructured the updated "Dynamic parameters" section
  [ZBXNEXT-10141] unified links to widgets#dynamic-parameters
  [ZBXNEXT-10141] unified "Time period" description; moved it to individual widget pages
  [ZBXNEXT-10141] moved "Override host" description to individual widget pages
  [ZBXNEXT-10141] removed redundant section (info already present where relevant)
  [ZBXNEXT-10141] updated "Dashboard widgets" page overview
  [ZBXNEXT-10141] removed outdated note (no deprecated widgets)