[gimp] build: update flatpak-howto.txt to build both 32 and 64-bit from...

[Jehan Pagès <jehanp src gnome org>]

commit 62652821156b80fc515576d106f7e7b66e202a88
Author: Jehan <jehan girinstud io>
Date:   Mon May 1 22:19:10 2017 +0200

    build: update flatpak-howto.txt to build both 32 and 64-bit from...
    
    ...same manifest.

 build/flatpak/flatpak-howto.txt |   19 +++++++++++++------
 1 files changed, 13 insertions(+), 6 deletions(-)
---
diff --git a/build/flatpak/flatpak-howto.txt b/build/flatpak/flatpak-howto.txt
index 94450c3..dd01307 100644
--- a/build/flatpak/flatpak-howto.txt
+++ b/build/flatpak/flatpak-howto.txt
@@ -60,9 +60,10 @@ Or simply update them:
 
>  "desktop-file-name-prefix": "(Dev) ",
 
-* Run the flatpak builder with the following command:
+* Run flatpak builder with the following commands:
 
-> flatpak-builder --repo=gimp-repo gimp-flatpak-build org.gimp.GIMP.json
+> flatpak-builder --arch=x86_64 gimp-flatpak-build-x86-64 org.gimp.GIMP.json
+> flatpak-builder --arch=i386 gimp-flatpak-build-i386 org.gimp.GIMP.json
 
   Note: if you ever want to check the `config.log` of any of the module,
   this is available in a hidden directory of your working path.
@@ -70,10 +71,16 @@ Or simply update them:
   The number will be incrementing at each build (`flatpak-builder`
   apparently caches every build).
 
-  If it ends successfuly, this will have built then installed GIMP in a
-  new folder `gimp-flatpak-build/` and all its dependencies based on the
-  information from the manifest. It will also create or update the
-  folder `gimp-repo` which is a flatpak repository.
+  If it ends successfuly, this will have built GIMP in new folders,
+  `gimp-flatpak-build-x86-64/` and `gimp-flatpak-build-i386/`
+  respectively.
+
+* Export the 2 builds:
+
+> flatpak build-export --gpg-sign=YOUR_GPG_KEY /path/to/repo gimp-flatpak-build-x86-64
+> flatpak build-export --gpg-sign=YOUR_GPG_KEY /path/to/repo gimp-flatpak-build-i386
+
+  The same repository will contain all the builds.
 
 * Test it with: