feat(#1974): enable experimental.git.async by default, see https://github.com/nvim-tree/nvim-tree.lua/issues/2104 (#2158)

doc/nvim-tree-lua.txt

@@ -436,7 +436,7 @@ applying configuration.
       },
       experimental = {
         git = {
-          async = false,
+          async = true,
         },
       },
       log = {
@@ -1206,13 +1206,14 @@ General UI configuration.
 
 *nvim-tree.experimental*
 Experimental features that may become default or optional functionality.
+In the event of a problem please disable the experiment and raise an issue.
 
     *nvim-tree.experimental.git.async*
     Direct file writes and `.git/` writes are executed asynchronously: the
     git process runs in the background. The tree updates on completion.
     Other git actions such as first tree draw and explicit refreshes are still
     done in the foreground.
-      Type: `boolean`, Default: `false`
+      Type: `boolean`, Default: `true`
 
 *nvim-tree.log*
 Configuration for diagnostic logging.

lua/nvim-tree.lua

@@ -561,7 +561,7 @@ local DEFAULT_OPTS = { -- BEGIN_DEFAULT_OPTS
   },
   experimental = {
     git = {
-      async = false,
+      async = true,
     },
   },
   log = {