Add Fml versioning (#542)

* Add FML version-based errors to the Q4 2023 whats newsletter

* Update experimenter branches doc to include fml version errors

docs/deep-dives/experimenter/branches.mdx

@@ -16,9 +16,11 @@ For non-desktop applications, the Feature Manifest Language (FML) is used to sur
 
 You can see that the save button validation has given us usable FML errors, including the line/col number that the error occurs at:
 
-<img src="/img/deep-dives/deeply-nested-fml-error.png"/>
+<img title="Deeply nested FML error" src="/img/deep-dives/deeply-nested-fml-error.png"/>
 
-The FML generates errors based on the **feature** you are using, the **application**, and the **channel**. Changing the channel on your experiment may result in different FML errors, since there may be differences between the feature manifests for each channel.
+<img title="FML Version error" src="/img/deep-dives/fml-version-error.png"/>
+
+The FML generates errors based on the **feature** you are using, the **application**, the **versions** of the application that you are targeting, and the **channel**. Changing the channel on your experiment may result in different FML errors, since there may be differences between the feature manifests for each version and channel.
 
 
 ## Desktop

docs/whats-news/2023/2023-q4.mdx

@@ -24,6 +24,8 @@ Coming soon...
 
 ## Experimenter
 
-🙌 FML error detection - [EXP-3873](https://mozilla-hub.atlassian.net/browse/EXP-3873), [EXP-2365](https://mozilla-hub.atlassian.net/browse/EXP-2365)
+🙌 FML error detection
 
-   > Error detection using the Feature Manifest Language is now available in Experimenter! For all applications that utilize the FML (non-desktop apps), the "Branches" page now uses the FML to detect when a feature configuration is invalid for the application's feature manifest. This is especially useful for deeply nested feature configurations. (erichards)
+   > Error detection using the Feature Manifest Language is now available in Experimenter! For all applications that utilize the FML (non-desktop apps), the "Branches" page now uses the FML to detect when a feature configuration is invalid for the application's feature manifest. This is especially useful for deeply nested feature configurations. (erichards) [EXP-3873](https://mozilla-hub.atlassian.net/browse/EXP-3873), [EXP-2365](https://mozilla-hub.atlassian.net/browse/EXP-2365)
+
+   > The FML also detects errors based on the specified versions that have been ch sen. For example, if you are targeting Fenix version 120 and the feature configuration shows errors for that version, you will now get helpful error messages that tell you _which_ version(s) of the feature manifest are throwing these errors. (erichards) [EXP-3875](https://mozilla-hub.atlassian.net/browse/EXP-3875)