Add -r option to ionotifywait in docker entrypoint

Before this, docker image will never detects that
`lightning-rpc` was created if it is running in regtest
or testnet, because the file will be created under
subfolder for each network name.
By recursively checking the file creation, now docker
can be run in any network configuration.

tools/docker-entrypoint.sh

@@ -8,7 +8,7 @@ if [ "$EXPOSE_TCP" == "true" ]; then
 
     echo "C-Lightning starting"
     while read -r i; do if [ "$i" = "lightning-rpc" ]; then break; fi; done \
-    < <(inotifywait  -e create,open --format '%f' --quiet "$LIGHTNINGD_DATA" --monitor)
+    < <(inotifywait -r -e create,open --format '%f' --quiet "$LIGHTNINGD_DATA" --monitor)
     echo "C-Lightning started"
     echo "C-Lightning started, RPC available on port $LIGHTNINGD_RPC_PORT"