awful.beautiful: fix comments

Signed-off-by: Julien Danjou <julien@danjou.info>

lib/awful/beautiful.lua.in

@@ -9,10 +9,12 @@ local package = package
 --- Beautiful module for awful
 module("awful.beautiful")
 
--- Exported variable handling theme
+-- Exported variable handling theme.
 theme = {}
 
---- Set the beautiful theme if any.
+--- Register the beautiful theme if beautiful is used.
+-- That allows various awful functions (and maybe other module using the
+-- awful.beautiful.get() method) to use colors theme as defined in beautiful.
 -- @param The beautiful theme.
 function register(btheme)
     if btheme then
@@ -22,7 +24,7 @@ function register(btheme)
     end
 end
 
---- Get the current registerde them.
+--- Get the current registered theme.
 -- @return The current theme table.
 function get()
     return package.loaded.awful.beautiful.theme