CODE_STYLE.md: fix broken link to INTERNALS

... the link would only work if browsed on GitHub, while this link now
takes the user to the website instead and thus should work on either.

Reported-by: David Demelier

docs/CODE_STYLE.md

@@ -28,8 +28,8 @@ other places of the code, just that the names should be logical,
 understandable and be named according to what they're used for. File-local
 functions should be made static. We like lower case names.
 
-See the [INTERNALS](INTERNALS.md) document on how we name non-exported
-library-global symbols.
+See the [INTERNALS](https://curl.se/dev/internals.html#symbols) document on
+how we name non-exported library-global symbols.
 
 ## Indenting