Clarify what a status is

Tests: web-platform-tests/wpt#27421.

Follow-up: #1156.

Closes #1142.

fetch.bs

@@ -985,11 +985,14 @@ user-agent-defined <a for=header>value</a> for the
 
 <h4 id=statuses>Statuses</h4>
 
-<p>A <dfn export id=concept-status>status</dfn> is a code.
+<p>A <dfn export id=concept-status>status</dfn> is an integer in the range 0 to 999, inclusive.
+
+<p class=XXX>Various edge cases in mapping HTTP/1's <code>status-code</code> to this concept are
+worked on in <a href=https://github.com/whatwg/fetch/issues/1156>issue #1156</a>.
 
 <p>A <dfn export>null body status</dfn> is a <a for=/>status</a> that is 101, 204, 205, or 304.
 
-<p>An <dfn export>ok status</dfn> is any <a for=/>status</a> in the range 200 to 299, inclusive.
+<p>An <dfn export>ok status</dfn> is a <a for=/>status</a> in the range 200 to 299, inclusive.
 
 <p>A <dfn export>redirect status</dfn> is a <a for=/>status</a> that is 301, 302, 303, 307, or 308.
 
@@ -7149,6 +7152,7 @@ Martin Dürst,
 Martin Thomson,
 Matt Andrews,
 Matt Falkenhagen,
+Matt Menke,
 Matt Oshry,
 Matt Seddon,
 Matt Womer,
@@ -7193,6 +7197,7 @@ Stephan Paul,
 Steven Salat,
 Sunava Dutta,
 Surya Ismail,
+Tab Atkins-Bittner,
 Takashi Toyoshima,
 吉野剛史 (Takeshi Yoshino),
 Thomas Roessler,