Clean up docs on roundup-sever SSL use.

Duplicate sections from man page update to admin_guide as the man
page often isn't installed anywhere man can find it.

Remove warning that SSL is only supported on python 3. Suprisingly my
change to fix it on Python 3 also inadvertantly fixed it on python 2.

Author: rouilj

doc/admin_guide.txt

@@ -181,11 +181,21 @@ Additional notes for each keyword:
   the variable "trackers" is available to the template and is a
   dict of all configured trackers.
 **ssl**
-  Enables the use of SSL to secure the connection to the roundup-server.
+  Enables use of SSL to secure the connection to the
+  roundup-server. In most cases, you will want to run a
+  real web server (Apache, Nginx) as a proxy to
+  roundup-server running without SSL.  The real web server
+  can filter/rate limit/firewall requests to roundup-server.
   If you enable this, ensure that your tracker's config.ini specifies
-  an *https* URL.
+  an *https* URL. See roundup-server.1 man page for
+  additional information.
 **pem**
   If specified, the SSL PEM file containing the private key and certificate.
+  The file must include both the private key and certificate with appropriate
+  headers (e.g. ``-----BEGIN PRIVATE KEY-----``,
+  ``-----END PRIVATE KEY-----`` and
+  ``-----BEGIN CERTIFICATE-----``,
+  ``-----END CERTIFICATE-----``.
   If not specified, roundup will generate a temporary, self-signed certificate
   for use.
 **trackers** section

share/man/man1/roundup-server.1

@@ -45,8 +45,7 @@ front end server to authenticate a user and pass the user identity to
 roundup.
 .TP
 \fB-s\fP
-Enables use of SSL. SSL only works when running the server using
-python 3. In most cases, you will want to run a real web server
+Enables use of SSL. In most cases, you will want to run a real web server
 (Apache, Nginx) as a proxy to roundup-server running without SSL.
 The real web server can filter/rate limit/firewall requests to
 roundup-server.