feat: add popup information (#1042)

doc/nvim-tree-lua.txt

@@ -616,6 +616,7 @@ INFORMATIONS				        *nvim-tree-info*
 - `W` will collapse the whole tree
 - `S` will prompt the user to enter a path and then expands the tree to match the path
 - `.` will enter vim command mode with the file the cursor is on
+- `C-k` will show file infos about the file under the cursor
 
 Defaults to:
 >
@@ -657,7 +658,8 @@ Defaults to:
       { key = "g?",                           action = "toggle_help" },
       { key = 'W',                            action = "collapse_all" },
       { key = "S",                            action = "search_node" },
-      { key = ".",                            action = "run_file_command" }
+      { key = ".",                            action = "run_file_command" },
+      { key = "<C-k>",                        action = "show_file_info" }
     }
 <
 The `list` option in `view.mappings.list` is a table of