JCF: Update README.md

docs/README.md

@@ -2,13 +2,13 @@
 
 To run one of the provided microservices in this repo, the basic command is the following:
 ```
-docker run --rm -e MICROSERVICE=<name of microservice> ghcr.io/dune-daq/microservices:39be
+docker run --rm -e MICROSERVICE=<name of microservice> ghcr.io/dune-daq/microservices:77df
 ```
 
 There are a couple of points to note:
 * The value of MICROSERVICE should be the name of a given microservice's subdirectory in this repo. As of Oct-6-2023, the available subdirectories are: `config-service`, `ers-dbwriter`, `logbook`, `opmon-dbwriter`, `runnumber-rest` and `runregistry-rest`. 
 * Most microservices require additional environment variables to be set, which can be passed using the usual docker syntax: `-e VARIABLE_NAME=<variable value>`
 * If you don't know what these additional environment variables are, you can just run the `docker` command as above without setting them; the container will exit out almost immediately but only after telling you what variables are missing
-* The `39be` tag for the image in the example above just refers to the first four characters of the git commit of the microservices repo whose `dockerfiles/Dockerfile.microservices` Docker file was used to create the image
+* The `77df` tag for the image in the example above just refers to the first four characters of the git commit of the microservices repo whose `dockerfiles/Dockerfile.microservices` Docker file was used to create the image. Currently [Oct-11-2023] this is the head of the `develop` branch. 
 
 For details on a given microservice, look at its own README file (format is `docs/README_<microservice name>.md`). They may or may not be up to date, however.