man: Document that current feature areas only work on Debian and derivatives

debian/changelog

@@ -10,6 +10,8 @@ dpkg (1.18.0) UNRELEASED; urgency=low
   * Document when and how the dpkg-maintscript-helper package name argument
     is or should be arch-qualified. Closes: #776072
   * Fix and update Arch substvar description in deb-substvars(5).
+  * Document that current build flag feature areas only work on Debian and
+    derivatives in dpkg-buildflags(1).
 
  -- Guillem Jover <guillem@debian.org>  Tue, 09 Dec 2014 23:53:18 +0100
 

man/dpkg-buildflags.1

@@ -135,8 +135,8 @@ the flag is set/modified by an environment-specific configuration.
 .TP
 .BI \-\-query\-features " area"
 Print the features enabled for a given area. The only currently recognized
-areas are \fBqa\fP, \fBreproducible\fP and \fBhardening\fP,
-see the \fBFEATURE AREAS\fP section for more details.
+areas on Debian and derivatives are \fBqa\fP, \fBreproducible\fP and
+\fBhardening\fP, see the \fBFEATURE AREAS\fP section for more details.
 Exits with 0 if the area is known otherwise exits with 1.
 .IP
 The output is in RFC822 format, with one section per feature.