DOC: intro: add a contacts section

This indicates where to find help and where to report bugs.
diff --git a/doc/intro.txt b/doc/intro.txt
index 7520ed1..dbec934 100644
--- a/doc/intro.txt
+++ b/doc/intro.txt
@@ -63,6 +63,8 @@
 4.3.      Varnish
 4.4.      Alternatives
 
+5. Contacts
+
 
 1. Available documentation
 --------------------------
@@ -1643,3 +1645,40 @@
 And similarly, since HAProxy and Varnish integrate so well together, it's easy
 to add it later into the mix to complement the feature set.
 
+
+5. Contacts
+-----------
+
+If you want to contact the developers or any community member about anything,
+the best way to do it usually is via the mailing list by sending your message
+to haproxy@formilux.org. Please note that this list is public and its archives
+are public as well so you should avoid disclosing sensitive information. A
+thousand of users of various experience levels are present there and even the
+most complex questions usually find an optimal response relatively quickly.
+Suggestions are welcome too. For users having difficulties with e-mail, a
+Discourse platform is available at http://discourse.haproxy.org/ . However
+please keep in mind that there are less people reading questions there and that
+most are handled by a really tiny team. In any case, please be patient and
+respectful with those who devote their spare time helping others.
+
+I you believe you've found a bug but are not sure, it's best reported on the
+mailing list. If you're quite convinced you've found a bug, that your version
+is up-to-date in its branch, and you already have a GitHub account, feel free
+to go directly to https://github.com/haproxy/haproxy/ and file an issue with
+all possibly available details. Again, this is public so be careful not to post
+information you might later regret. Since the issue tracker presents itself as
+a very long thread, please avoid pasting very long dumps (a few hundreds lines
+or more) and attach them instead.
+
+If you've found what you're absolutely certain can be considered a critical
+security issue that would put many users in serious trouble if discussed in a
+public place, then you can send it with the reproducer to security@haproxy.org.
+A small team of trusted developers will receive it and will be able to propose
+a fix. We usually don't use embargoes and once a fix is available it gets
+merged. In some rare circumstances it can happen that a release is coordinated
+with software vendors. Please note that this process usually messes up with
+eveyone's work, and that rushed up releases can sometimes introduce new bugs,
+so it's best avoided unless strictly necessary; as such, there is often little
+consideration for reports that needlessly cause such extra burden, and the best
+way to see your work credited usually is to provide a working fix, which will
+appear in changelogs.