README: describe OSTREE_BRANCHNAME.
Not sure how that one got away for so long! It's one of the most
commonly used, after all.
@@ -99,6 +99,7 @@ Your images will also need network connectivity to be able to reach an actual OT
== SOTA-related variables in local.conf
+* `OSTREE_BRANCHNAME` - OSTree branch name. Defaults to `${SOTA_HARDWARE_ID}`. Particularly useful for grouping similar images.
* `OSTREE_REPO` - path to your OSTree repository. Defaults to `$\{DEPLOY_DIR_IMAGE}/ostree_repo`
* `OSTREE_OSNAME` - OS deployment name on your target device. For more information about deployments and osnames see the https://ostree.readthedocs.io/en/latest/manual/deployment/[OSTree documentation]. Defaults to "poky".
* `OSTREE_COMMIT_BODY` - Message attached to OSTree commit. Empty by default.
