make update key customisable, and change wording on a comment

eatit-cfg.lua

@@ -29,6 +29,7 @@ plugins = { -- the  plugins you want to load
 
 -- options for eat it
 opts = {
+  bind = 'U',
   logging = { -- options for logging
     log = true,
     logdate = '[%H:%M:%S]:',
@@ -36,6 +37,6 @@ opts = {
   },
   dl = { -- options for dealing with the git repos
     dir = '/tmp/mpv-eatit',
-    powerwash = false, -- if true the tmp dir gets deleted after mpv closes
+    powerwash = false, -- if true the dl dir gets deleted after mpv closes
   }
 }