tar: Comment spelling fixes

Author: scop

completions/tar

@@ -403,7 +403,7 @@ __tar_try_list_archive()
     __tar_extract_like_mode || return 1
 
     # This all is just to approach directory completion from "virtual"
-    # directory structure in tarbal (for which the _filedir is unusable)
+    # directory structure in tarball (for which the _filedir is unusable)
 
     set -- "${words[@]}"
     tarbin=$1
@@ -576,7 +576,7 @@ _gtar()
                 # continue also
                 $split && break
 
-                # Most probably, when code goes here, the PREV varibale contains
+                # Most probably, when code goes here, the PREV variable contains
                 # some string from "$long_arg_none" and we want continue.
                 ;;
             -[a-zA-Z0-9?])