apt-cache(8): Mention that --names-only search provides

Closes: #618017

doc/apt-cache.8.xml

@@ -172,7 +172,7 @@ Reverse Provides:
      If <option>--full</option> is given
      then output identical to <literal>show</literal> is produced for each matched
      package, and if <option>--names-only</option> is given then the long description
-     is not searched, only the package name is.</para>
+     is not searched, only the package name and provided packages are.</para>
      <para>
      Separate arguments can be used to specify multiple search patterns that 
      are and'ed together.</para></listitem>
@@ -319,7 +319,7 @@ Reverse Provides:
      </varlistentry>
 
      <varlistentry><term><option>--names-only</option></term><term><option>-n</option></term>
-     <listitem><para>Only search on the package names, not the long descriptions. 
+     <listitem><para>Only search on the package and provided package names, not the long descriptions.
      Configuration Item: <literal>APT::Cache::NamesOnly</literal>.</para></listitem>
      </varlistentry>