chore(base parser): Bolden example

Author: tony

libvcs/parse/base.py

@@ -112,7 +112,7 @@ def register(self, cls: Matcher) -> None:
         >>> GitURL.is_valid(url='gitlab:vcs-python/libvcs')
         True
 
-        git URLs + pip-style git URLs:
+        **Example: git URLs + pip-style git URLs:**
 
         This is already in :class:`GitURL` via :data:`PIP_DEFAULT_MATCHERS`. For the
         sake of showing how extensibility works, here is a recreation based on