coretasks: better interactive help for .blocks command

Eliminated the link (to a webpage we're probably going to delete) in
favor of directly specifying the available arguments, and added an
example of how to `del` a block. (The only examples before were `add`.)

sopel/coretasks.py

@@ -1353,16 +1353,17 @@ def _get_sasl_pass_and_mech(bot):
 
 
 @plugin.commands('blocks')
+@plugin.example(r'.blocks del nick falsep0sitive', user_help=True)
 @plugin.example(r'.blocks add host some\.malicious\.network', user_help=True)
 @plugin.example(r'.blocks add nick sp(a|4)mb(o|0)t\d*', user_help=True)
 @plugin.thread(False)
 @plugin.unblockable
 @plugin.priority('low')
 @plugin.require_admin
 def blocks(bot, trigger):
-    """
-    Manage Sopel's blocking features.
-    See https://sopel.chat/usage/ignoring-people/ for usage notes.
+    """Manage Sopel's blocking features.
+
+    Full argspec: `list [nick|host]` or `[add|del] [nick|host] pattern`
     """
     STRINGS = {
         "success_del": "Successfully deleted block: %s",