tf-a-lts-docs-watcher.sh: Use "slug" instead of "verbose_name"

When querying older version to hide, use "slug" property to pass to further
API calls instead of "verbose_name", because slugs is what API expects.
(Verbose name is an actual git tag, which can be "foo/Bar", which gets
converted to slug "foo-bar").

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I599e0e9bfd8ee93ddfe92a6a6f04c0c4ccfa4c36
diff --git a/scripts/tf-a-lts-docs-watcher.sh b/scripts/tf-a-lts-docs-watcher.sh
index 45c0541..f8d4272 100755
--- a/scripts/tf-a-lts-docs-watcher.sh
+++ b/scripts/tf-a-lts-docs-watcher.sh
@@ -60,7 +60,7 @@
     echo -e "\nNew release tag: ${new_tag}"
     # Hide the current active and unhidden tags
     old_tags=$(curl -s -H "Authorization: Token ${RTD_API_TOKEN}" "${RTD_VER_API}/?slug=${lts_branch}&type=tag&active=true" | \
-                   jq -r '.results | map(select(.hidden == false) | .verbose_name) | .[]')
+                   jq -r '.results | map(select(.hidden == false) | .slug) | .[]')
     for t in ${old_tags};
     do
         echo "Hide old tag: ${t}"