SPEC: false statements fixed, repeats removed, dropped requirements restored

The bounds sentence, the blocklist URL sentence, the deny list sentence,
the limit action's scope and the observe mode sentence now say what the
code does. Each of the twenty-one requirements the fourth review found
twice is stated once, with a link from the other place. The request id
header, redirect_uri's case, change 4's reason and the live archive's
InRelease files are back. The biased thresholds are defined where they
are introduced. The docs files apply the fifth README review's findings
and stay identical to the README branch.

Model: fable-5-1

docs/alerts.md

@@ -78,11 +78,14 @@ on one line:
 
 - `instance`: `SWWAF_INSTANCE_NAME`. `time`: when the alert was raised. `event`:
   one of the events above.
-- `client`: the address whose request raised the alert. `netblock`: the ban's
-  netblock, the netblock an anomaly counted, or, for the other events, the
-  client as rate limiting counts it: an IPv4 address as a /32, or an IPv6 group.
-  Both are empty for `source_failure` and `file_error`.
-- `asn`, `as_name` and `country`: the client's as known when the alert was
+- `client`: the address whose request raised the alert. Empty for
+  `source_failure` and `file_error`.
+- `netblock`: empty for `source_failure` and `file_error`; otherwise one of:
+    - the ban's netblock;
+    - the netblock an anomaly counted;
+    - for the other events, the client as rate limiting counts it: an IPv4
+      address as a /32, or an IPv6 group.
+- `asn`, `as_name` and `country`: the client's, as known when the alert was
   raised. They are empty when GeoJS had not answered yet.
 - `reason`: a short sentence, such as
   `requests per minute over the limit of 1000` or `listed by a blocklist`.