update default focus_preview mapping

Author: ttytm

README.md

@@ -200,7 +200,7 @@ use {
             ["<cr>"] = "open",
             ["<esc>"] = "revert_preview",
             ["P"] = { "toggle_preview", config = { use_float = true } },
-            ["gp"] = "focus_preview"
+            ["l"] = "focus_preview"
             ["S"] = "open_split",
             ["s"] = "open_vsplit",
             -- ["S"] = "split_with_window_picker",

doc/neo-tree.txt

@@ -195,7 +195,7 @@ z         = close_all_nodes: Close all nodes in the tree.
 
 P          = toggle_preview: Toggles "preview mode", see |neo-tree-preview-mode| 
 
-gp         = focus_preview: Focuses active preview window
+l          = focus_preview: Focus the active preview window
 
 <esc>      = revert_preview: Ends "preview_mode" if it is enabled, and reverts
                              any preview windows to what was being shown before

lua/neo-tree/defaults.lua

@@ -312,7 +312,7 @@ local config = {
       ["<cr>"] = "open",
       ["<esc>"] = "revert_preview",
       ["P"] = { "toggle_preview", config = { use_float = true } },
-      ["gp"] = "focus_preview",
+      ["l"] = "focus_preview",
       ["S"] = "open_split",
       -- ["S"] = "split_with_window_picker",
       ["s"] = "open_vsplit",