documentation

Pull request #730: feature/ZBXNEXT-8087-6.4-D feat. ZBXNEXT-1111 (Removal of template nesting & added template versioning).

Merge in WEB/documentation from feature/ZBXNEXT-8087-6.4-D to release/6.4

* commit '160b932169a2fd9a326473ea0b696ffeddd9a732': (30 commits)
  [ZBXNEXT-8087] Removed template nesting (removed mention of inherited tags)
  [ZBXNEXT-8087] Removed template nesting (updated "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (minor wording fixes in "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (minor wording fixes in "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (updated "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (updated "What's new", "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (updated "What's new", "Upgrade notes", "Templates" export/import)
  [ZBXNEXT-1111] Updated templates location from "templates" to "zabbix/templates"
  [ZBXNEXT-1111] Template versioning (updated grammar in "What's new", "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (updated heading hierarchy in "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (fixed multiple images, pages)
  [ZBXNEXT-8087] Added link to "Upgrade notes"; updated wording in "Trigger dependencies"
  [ZBXNEXT-8087] Removed template nesting (updated "New template" page in "Quickstart" section)
  [ZBXNEXT-1111] Template versioning (updated multiple pages)
  [ZBXNEXT-8087] Removed template nesting (updated "What's new", "Upgrade notes")
  [ZBXNEXT-8087] Removed template nesting (updated "What's new", "Upgrade notes", "Linking/unlinking", templates.png)
  [ZBXNEXT-8087] Removed template nesting (updated multiple images)
  [ZBXNEXT-8087] Removed template nesting (updated "What's new")
  [ZBXNEXT-8087] Removed template nesting (updated template config images)
  [ZBXNEXT-8087] Removed template nesting (updated "Tags" filter description)
  ...