[gimp-web/testing] Add indication about `flatpak update`.

[Jehan <jehanp src gnome org>]

commit 7060073472afff8dd9957309ce996d1598612db7
Author: Jehan <jehan girinstud io>
Date:   Tue Jan 22 15:03:44 2019 +0100

    Add indication about `flatpak update`.
    
    We are not going to make a complete tutorial about flatpak, but the
    update command is still a base/important command, and it seems some
    people did not realize that flatpak installation will also provide
    updates (so they stick to whatever version when they first installed).
    Well the best is not to have to care about CLI, but not all
    distributions out there have GUI support for flatpak (yet?).

 themes/newgimp/templates/downloads.html | 13 +++++++++++++
 1 file changed, 13 insertions(+)
---
diff --git a/themes/newgimp/templates/downloads.html b/themes/newgimp/templates/downloads.html
index cb115696..476b4cb6 100644
--- a/themes/newgimp/templates/downloads.html
+++ b/themes/newgimp/templates/downloads.html
@@ -94,6 +94,19 @@
         <p>
         <code>flatpak run org.gimp.GIMP//stable</code>
         </p>
+        <p>
+        This installation will also provide regular update. You don't
+        have to come back on this page and install again (it will not
+        work!) when a new version of GIMP is released. Instead if your
+        distribution and/or desktop has a good support for flatpak, it
+        should propose to perform updates.
+        <br/>
+        Once again, if your distribution does not have proper support,
+        you can always fall back to using the following command line:
+        </p>
+        <p>
+        <code>flatpak update</code>
+        </p>
         <h3>Systems without flatpak support</h3>
         <p>
             GIMP can also run on Solaris and is available for the BSD family of systems such as FreeBSD and 
OpenBSD.