MISC: Update contributing, don't use __, prefer ___

CONTRIBUTING.md

@@ -46,10 +46,11 @@ script found at the root of the build tree: `./debug lektord`.
 
 ### C code and style
 
-Prefer using `}` names for static variables and functions. Prefix the
-name of the file or folder in function names, e.g. `database_` or
-`command_`. If you declare functions that really nobody should used,
-please prefix them with three underscores like `___${name}`.
+Prefer using `___` prefixed names for static variables and functions.
+Prefix the name of the file or folder in function names, e.g.
+`database_` or `command_`. If you declare functions that really nobody
+should used, please prefix them with three underscores like
+`___dothing`. General functions are prefixed `lkt_`.
 
 For formating, use the `./utils/scripts/style.bash` from the root of
 the project. You'll need `clang-format` for it to works.