docs: restore default highlighting keywords and options in HTML

Keywords and options recently got dedicated highlighting roles in
b3626d48e (Highlight keywords differently, 2021-02-04) and
711796ad1 (Highlight options differently, 2021-10-19)
but still default to "command" and "parameter", respectively.

The dedicated roles were not colored by our CSS theme,
which makes a "test -f foo.txt" look weird:
- "test" is dark blue (since it's a command)
- "foo.txt" is light blue (since it's a parameter)
- "-f" is black (weird!)

The CSS theme doesn't support configuration, so the dedicated
highlighting roles should always default to their fallback
options. Make it so.

doc_src/fish_indent_lexer.py

@@ -5,7 +5,6 @@
 
 from pygments.lexer import Lexer
 from pygments.token import (
-    Keyword,
     Name,
     Comment,
     String,
@@ -30,10 +29,10 @@ ROLE_TO_TOKEN = {
     "normal": Name.Variable,
     "error": Generic.Error,
     "command": Name.Function,
-    "keyword": Keyword,
+    "keyword": Name.Function,
     "statement_terminator": Punctuation,
     "param": Name.Constant,
-    "option": Name.Literal,
+    "option": Name.Constant,
     "comment": Comment,
     "match": DEFAULT,
     "search_match": DEFAULT,