tf-a-lts-docs-watcher.sh: Wait for build to finish and output docs URL

So that once the build is finished we know that the docs are actually
available on ReadTheDocs.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I8351d7dd055e87aea2e90f3f136e75930899aa88
diff --git a/scripts/tf-a-lts-docs-watcher.sh b/scripts/tf-a-lts-docs-watcher.sh
index 29ef47b..7b6f1ca 100755
--- a/scripts/tf-a-lts-docs-watcher.sh
+++ b/scripts/tf-a-lts-docs-watcher.sh
@@ -112,5 +112,8 @@
     # Active the new version
     echo "Active new version: ${new_slug}"
     activate_version ${new_slug}
+
+    wait_for_build ${new_slug}
+    echo "Docs for the new release are available at: https://${RTD_PROJECT}.readthedocs.io/en/${new_slug}/"
 fi