flatpak: Clarify use of the "single-file bundle" terminology

https://phabricator.apertis.org/T8592



Signed-off-by: Ryan Gonzalez <ryan.gonzalez@collabora.com>

content/guides/flatpak.md

@@ -504,7 +504,7 @@ design document.
 Flatpak application signatures occur on several levels:
   * single commits
   * whole repositories
-  * single-file bundles
+  * [single-file bundles]({{< ref "#publishing-a-single-file-bundle" >}})
 
 Please note, however, that GPG signatures, the upstream default, are disabled on
 Apertis. It is still possible to pull from GPG-signed repositories, but those
@@ -532,7 +532,7 @@ following flatpak commands:
   * `flatpak build-update-repo`
 
 These commands allow one to create Ed25519-signed commits from an unsigned
-repository or bundle, or to create signed bundles as explained below.
+repository or single-file bundle, or to create signed bundles as explained below.
 
 Multiple occurrences of the `--sign` option are allowed in to order to permit
 multiple signatures of each object.
@@ -674,7 +674,14 @@ IsRuntime=false
 SignatureKey=B3a86SmB+sby/N5onaxTXjK1OEAbZOI2fsdr3kKD+KE=
 ```
 
-### Publishing a bundle
+### Publishing a single-file bundle
+
+{{% notice info %}}
+The concept of "bundles" within Flatpak is unrelated to the Apertis-specific
+term ["application bundles"]({{< ref "glossary.md#application-bundles" >}}). For
+clarity, the concept described in this section will be referred to as a
+"single-file bundle".
+{{% /notice %}}
 
 Flatpak applications can also be distributed as
 [single-file bundles](https://docs.flatpak.org/en/latest/single-file-bundles.html),