Grammar of identifiers: correct link to keywords page

Author: brauliobz

src/identifiers.md

@@ -28,6 +28,6 @@ that does _not_ occur in the set of [keywords].
 
 [`XID_start`]:  http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Start%3A%5D&abb=on&g=&i=
 [`XID_continue`]: http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Continue%3A%5D&abb=on&g=&i=
-[keywords]: ../grammar.html#keywords
+[keywords]: keywords.html
 [^non_ascii_idents]: Non-ASCII characters in identifiers are currently feature
   gated. This is expected to improve soon.