man: Document the obsolete dpkg --compare-versions operators in dpkg(1)

[guillem@debian.org:
 - Tiny wording and formatting tweaks. ]

Closes: #776551
Signed-off-by: Guillem Jover <guillem@debian.org>

debian/changelog

@@ -59,6 +59,9 @@ dpkg (1.18.0) UNRELEASED; urgency=low
   * Use strftime() instead of «date -R» in dpkg-genchanges, as the latter
     is not specified by POSIX and is not widely portable.
   * Warn on obsolete '<' and '>' operators in dpkg --compare-versions.
+  * Document the obsolete --compare-versions '<' and '>' operators in the
+    dpkg(1) man page. Thanks to Tomas Pospisek <tpo_hp@sourcepole.ch>.
+    Closes: #776551
 
   [ Updated manpages translations ]
   * German (Helge Kreutzmann).

man/dpkg.1

@@ -331,7 +331,9 @@ two groups of operators, which differ in how they treat an empty
 version: \fBlt le eq ne ge gt\fP. These treat an empty version as later
 than any version: \fBlt\-nl le\-nl ge\-nl gt\-nl\fP. These are provided
 only for compatibility with control file syntax: \fB< << <= = >= >>
->\fP.
+>\fP. The \fB<\fP and \fB>\fP operators are obsolete and should \fBnot\fP
+be used, due to confusing semantics. To illustrate: \fB0.1 < 0.1\fP
+evaluates to true.
 .\" .TP
 .\" .B \-\-command\-fd \fIn\fP
 .\" Accept a series of commands on input file descriptor \fIn\fP. Note: