doc/guide: do not advertise pkglint -Call anymore

This option was kind of useful when the -Cextra option still existed (up
to 2019-02-19). After that date, it only enabled checks for the pkgsrc
infrastructure files, inter-package checks, as well as other checks on
files unrelated to the current package. These checks tend to be more
confusing than being helpful when checking a single package. They are
still useful when checking the whole pkgsrc tree at once, but that's a
special case.

doc/guide/files/examples.xml

@@ -1,4 +1,4 @@
-<!-- $NetBSD: examples.xml,v 1.14 2013/04/07 21:04:44 wiz Exp $ -->
+<!-- $NetBSD: examples.xml,v 1.15 2020/01/28 03:15:47 rillig Exp $ -->
 
 <appendix id="examples">
   <title>A simple example package: bison</title>
@@ -70,7 +70,7 @@ share/bison.hairy
 looks fine.</screen>
 
       <para>Depending on the supplied command line arguments (see pkglint(1)),
-	more checks will be performed. Use e.g. <command>pkglint -Call
+	more checks will be performed. Use e.g. <command>pkglint
 	-Wall</command> for a very thorough check.</para>
     </sect2>
   </sect1>