Name log fields, metrics and the Core Rule Set package for what they are (closes #192)

Log field, metric, action and event names now say what they count
and, for timings, the unit. Package internal/waf is internal/coreruleset.

Model: opus-5-5

docs/state-files.md

@@ -64,8 +64,8 @@ since it was first seen:
 - body bytes of its requests, and of the responses it was sent;
 - responses by status class;
 - offences by kind: `limit`, `attack`, `blocked_by_block_rule` and
-  `waf_blocked`. A file may also hold `token_refused`, which is kept, and which
-  nothing adds to.
+  `blocked_by_core_rule_set`. A file may also hold `token_refused`, which is
+  kept, and which nothing adds to.
 
 ## `lookups.json`