Fix highlight error

 add highliht of `do:` remove highlight of `function`

Author: jsvisa

syntax/elixir.vim

@@ -16,8 +16,8 @@ syn match elixirComment '#.*' contains=elixirTodo
 syn keyword elixirTodo FIXME NOTE TODO OPTIMIZE XXX HACK contained
 
 syn keyword elixirKeyword is_atom is_binary is_bitstring is_boolean is_float is_function is_integer is_list is_number is_pid is_port is_record is_reference is_tuple is_exception
-syn keyword elixirKeyword case cond bc lc inlist inbits if unless try receive function
-syn keyword elixirKeyword exit raise throw after rescue catch else
+syn keyword elixirKeyword case cond bc lc inlist inbits if unless try receive
+syn keyword elixirKeyword exit raise throw after rescue catch else do
 syn keyword elixirKeyword quote unquote super
 syn match elixirKeyword '\<\%(->\)\>\s*'