Revert README as preview-{fg,bg} are only available on master

CHANGELOG.md

@@ -9,8 +9,6 @@ CHANGELOG
       --color 'fg:#bbccdd,fg+:#ddeeff,bg:#334455,preview-bg:#223344,border:#778899' \
       --border --height 20 --layout reverse --info inline
   ```
-- Preview window border can be disabled by setting `noborder` in
-  `--preview-window`
 - Removed the immediate flicking of the screen on `reload` action.
   ```sh
   : | fzf --bind 'change:reload:seq {q}' --phony

README.md

@@ -510,13 +510,10 @@ fzf --preview 'bat --style=numbers --color=always {} | head -500'
 ```
 
 You can customize the size, position, and border of the preview window using
-`--preview-window` option, and the foreground and background color of it with
-`--color` option. For example,
+`--preview-window` option.
 
 ```bash
-fzf --height 40% --layout reverse --info inline --border \
-    --preview 'file {}' --preview-window down:1:noborder \
-    --color 'fg:#bbccdd,fg+:#ddeeff,bg:#334455,preview-bg:#223344,border:#778899'
+fzf --height 40% --layout reverse --preview 'file {}' --preview-window down:1
 ```
 
 See the man page (`man fzf`) for the full list of options.