tf-a-lts-docs-watcher.sh: Fix timing issue

When a new lts tag is created, it needs some time to let RTD
aware of it. So, checking the version status in a loop, once
RTD knows it, activate it right away

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: Ibab3247fd303101e091b26459a2fe46a1045df66
1 file changed