tf-a-lts-docs-watcher.sh: Convert Git tag to ReadTheDocs slug

There's not really one-to-one mapping between git tag and corresponding
RTD version slug, as soon as we get to more complex tags. For example,
tag "sandbox/lts-v2.10.3-20240229T100000" gets mapped by RTD to slug
"sandbox-lts-v2.10.3-20240229t100000". So, perform the mapping on our
side to get feed proper data to the RTD API.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: If785cd31f25d6b2835c8b8b761ffad817765bf4b
diff --git a/scripts/tf-a-lts-docs-watcher.sh b/scripts/tf-a-lts-docs-watcher.sh
index f8d4272..ae50e98 100755
--- a/scripts/tf-a-lts-docs-watcher.sh
+++ b/scripts/tf-a-lts-docs-watcher.sh
@@ -18,6 +18,8 @@
 
 function activate_version() {
     version=$1
+    # Convert tag to ReadTheDocs version slug
+    version=$(echo ${version} | tr '[A-Z]/' '[a-z]-')
     max_retry_time=20
     retry=0