fix workers-doc-to-yaml

roles/custom/matrix-synapse/files/workers-doc-to-yaml.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 # Fetch the synapse worker documentation and extract endpoint URLs
 # matrix-org/synapse master branch points to current stable release
+# and put it between `workers:start` and `workers:end` tokens in ../vars/main.yml
 
-URL=https://github.com/matrix-org/synapse/raw/master/docs/workers.md
-curl -L ${URL} | awk -f workers-doc-to-yaml.awk > ../vars/workers.yml
+snippet="$(curl -L https://github.com/matrix-org/synapse/raw/master/docs/workers.md | awk -f workers-doc-to-yaml.awk)"
+awk -v snippet="$snippet" -i inplace '/workers:start/{f=1;print;print snippet}/workers:end/{f=0}!f' ../vars/main.yml