message: Document the surround feature
  Related to
diff: @@ -32,6 +32,7 @@ One million downloads! This project won't be successful without contributions fr
  - To add a multi-cursor to the current environment name, call _LaTeX Workshop: Add a multi-cursor to the current environment name_ from the **Command Palette** (command `latex-workshop.multicursor-envname` ). For this command to work, the cursor must be strictly between `\begin{...}` and `\end{...}`. Repeated calls result in selecting the outer environments.
  - [Snippets](snippets/snippets-doc.md)
  - A lot of LaTeX commands can be typed using snippets starting in `\`, then type part of the command to narrow the search.
  + - Surround some selected text with a LaTeX command by pressing `\` after selecting some text. A new menu pops up to select the command. This feature is enabled when `latex-workshop.intellisense.surroundCommand.enabled` is set to `true`, default is `false`.
  - We also provide a few other snippets mechanisms
  - Greek letters are obtained as `@` + `letter`. Some letters have variants, which are available as `@v` + `letter`. See [here](snippets/snippets-doc.md#greek-letters).
  - Common environments can be obtained by `BXY` where `XY` are the first two letters of the environment name, eg. `BEQ` gives the `equation` environment. If you want the star version of the environment, use `BSXX`, eg. `BSEQ` gives the `equation*` environment. See [here](snippets/snippets-doc.md#environments).
  