hacking: Improve 'git send-email' documentation

For the benefit of first time contributors, we point out that 'git
send-email' might have to be installed separately; however, we omit
the fact that some configuration will likely be needed before it
can successfully deliver patches to the mailing list.

Some minor tweaks to the existing contents are included as well.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

docs/hacking.html.in

@@ -29,8 +29,8 @@
         file from zanata.</p>
       </li>
 
-      <li><p>Post patches using "git send-email", with git rename
+      <li><p>Post patches using <code>git send-email</code>, with git
-        detection enabled.  You need a one-time setup of:</p>
+        rename detection enabled.  You need a one-time setup of:</p>
 <pre>
   git config diff.renames true
 </pre>
@@ -50,22 +50,44 @@
   git pull --rebase
   (fix any conflicts)
   git send-email --cover-letter --no-chain-reply-to --annotate \
-                 --to=libvir-list@redhat.com master
+                 --confirm=always --to=libvir-list@redhat.com master
 </pre>
-        <p>(Note that the "git send-email" subcommand may not be in
+        <p>For a single patch you can omit
-        the main git package and using it may require installation of a
-        separate package, for example the "git-email" package in
-        Fedora.)  For a single patch you can omit
         <code>--cover-letter</code>, but a series of two or more
-        patches needs a cover letter. If you get tired of typing
+        patches needs a cover letter.</p>
-        <code>--to=libvir-list@redhat.com</code> designation you can
+        <p>Note that the <code>git send-email</code> subcommand may not
-        set it in git config:</p>
+        be in the main git package and using it may require installation
+        of a separate package, for example the "git-email" package in
+        Fedora and Debian.  If this is your first time using
+        <code>git send-email</code>, you might need to configure it to
+        point it to your SMTP server with something like:</p>
+<pre>
+  git config --global sendemail.smtpServer stmp.youremailprovider.net
+</pre>
+        <p>If you get tired of typing
+        <code>--to=libvir-list@redhat.com</code> all the time, you can
+        configure that to be automatically handled as well:</p>
 <pre>
   git config sendemail.to libvir-list@redhat.com
 </pre>
+        <p>As a rule, patches should be sent to the mailing list only: all
+        developers are subscribed to libvir-list and read it regularly, so
+        please don't CC individual developers unless they've explicitly
+        asked you to.</p>
+        <p>Avoid using mail clients for sending patches, as most of them
+        will mangle the messages in some way, making them unusable for our
+        purposes.  Gmail and other Web-based mail clients are particularly
+        bad at this.</p>
+        <p>If everything went well, your patch should show up on the
+        <a href="https://www.redhat.com/archives/libvir-list/">libvir-list
+        archives</a> in a matter of minutes; if you still can't find it on
+        there after an hour or so, you should double-check your setup.  Note
+        that your very first post to the mailing list will be subject to
+        moderation, and it's not uncommon for that to take around a day.</p>
         <p>Please follow this as close as you can, especially the rebase and
-        git send-email part, as it makes life easier for other developers to
+        <code>git send-email</code> part, as it makes life easier for other
-        review your patch set. One should avoid sending patches as attachments,
+        developers to review your patch set.</p>
+        <p>One should avoid sending patches as attachments,
         but rather send them in email body along with commit message. If a
         developer is sending another version of the patch (e.g. to address
         review comments), they are advised to note differences to previous