Proposals for cheat-sheet docs (#12946)

* Propose additional settings in cheat sheet

Add most used settings of app.ini to cheat sheet docs.

* Fix small typo

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -134,7 +134,8 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 - `FEED_PAGING_NUM`: **20**: Number of items that are displayed in home feed.
 - `GRAPH_MAX_COMMIT_NUM`: **100**: Number of maximum commits shown in the commit graph.
 - `DEFAULT_THEME`: **gitea**: \[gitea, arc-green\]: Set the default theme for the Gitea install.
-- `THEMES`:  **gitea,arc-green**: All available themes. Allow users select personalized themes
+- `SHOW_USER_EMAIL`: **true**: Whether the email of the user should be shown in the Explore Users page.
+- `THEMES`:  **gitea,arc-green**: All available themes. Allow users select personalized themes.
   regardless of the value of `DEFAULT_THEME`.
 - `REACTIONS`: All available reactions users can choose on issues/prs and comments
     Values can be emoji alias (:smile:) or a unicode emoji.
@@ -150,6 +151,12 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 - `NOTICE_PAGING_NUM`: **25**: Number of notices that are shown in one page.
 - `ORG_PAGING_NUM`: **50**: Number of organizations that are shown in one page.
 
+### UI - Metadata (`ui.meta`)
+
+- `AUTHOR`: **Gitea - Git with a cup of tea**: Author meta tag of the homepage.
+- `DESCRIPTION`: **Gitea (Git with a cup of tea) is a painless self-hosted Git service written in Go**: Description meta tag of the homepage.
+- `KEYWORDS`: **go,git,self-hosted,gitea**: Keywords meta tag of the homepage.
+
 ### UI - Notification (`ui.notification`)
 
 - `MIN_TIMEOUT`: **10s**: These options control how often notification endpoint is polled to update the notification count. On page load the notification count will be checked after `MIN_TIMEOUT`. The timeout will increase to `MAX_TIMEOUT` by `TIMEOUT_STEP` if the notification count is unchanged. Set MIN_TIMEOUT to 0 to turn off.
@@ -710,5 +717,5 @@ Task queue configuration has been moved to `queue.task`. However, the below conf
 ## Other (`other`)
 
 - `SHOW_FOOTER_BRANDING`: **false**: Show Gitea branding in the footer.
-- `SHOW_FOOTER_VERSION`: **true**: Show Gitea version information in the footer.
+- `SHOW_FOOTER_VERSION`: **true**: Show Gitea and Go version information in the footer.
 - `SHOW_FOOTER_TEMPLATE_LOAD_TIME`: **true**: Show time of template execution in the footer.