Update instructions

Author: niting3c

README.md

@@ -9,12 +9,13 @@ Major and minor version follow the envoy version against which they are built. T
 
 The `tools` directory follows https://github.com/envoyproxy/java-control-plane/commits/main/tools as closely as possible.
 
-1. Update the `API_SHAS` (which are not really just SHAs): run `update-sha.sh MAJOR.MINOR.PATCH`, paste the end of its output to `API_SHAS`.
-
-1. Update the proto files using `update-api.sh`. This will remove the old `src/main/proto` and fetch a new set of protos.
-
-1. Bump the library version accoring to `Versioning` above in `gradle.properties`.
-
-1. Now it should build on CI. Can try locally using `./gradlew assemble`, but see GHA workflow for specific steps.
+1. Grab the Commit ID of the envoy version you are going to use and update it into the `API_SHAS` file.
+2. Next see its Bazel dependencices `https://github.com/envoyproxy/envoy/blob/{GITHUB_COMMIT_ID}/api/bazel/repository_locations.bzl`
+3. Update the remaining SHAs and Versions in the `API_SHAS` file. 
+4. This is an alternate : you can also use the run `update-sha.sh MAJOR.MINOR.PATCH`, paste the end of its output to `API_SHAS`.
+5. Update the proto files using `update-api.sh`. This will remove the old `src/main/proto` and fetch a new set of protos.
+6. Bump the library version according to `Versioning` above in `gradle.properties`.
+7. Now it should build on CI. Can try locally using `./gradlew assemble`, but see GHA workflow for specific steps.
+8. You may need to add or remove protos depending on the failures and you would want to refer to the bazel dependencies file to figure out what failed, finally udpate the scripts to have the change.
 
 Note: until we catch up with Envoy head version, slight adjustments might be needed for these scripts, towards matching upstream more closely.