gitignore: ignore .vscode directory

The directory is created by Visual Studio Code editor to store its
local state.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>

.gitignore

@@ -30,6 +30,7 @@ cscope.out
 cscope.po.out
 .config
 .vimrc
+.vscode
 
 dist
 stubdom/*.tar.gz