diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index fb3eda7bc5..f874279aa7 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -8,6 +8,10 @@ To build the core project, run `make` from the repository root.  This will resul
 
 To remove built artifacts, use `make clean`.
 
+### Build affecting environment variables
+* `FUNC_REPO_REF` affects which github repo will be used to fetch tekton tasks for on cluster build. Default: `knative/func`.
+* `FUNC_REPO_BRANCH_REF` affects which github branch will be used to fetch tekton tasks for on cluster build. Default: `main`.
+
 ## Testing
 
 To run core unit tests, use `make test`.
diff --git a/docs/building-functions/on_cluster_build.md b/docs/building-functions/on_cluster_build.md
index 77f429f30b..47e75d1c28 100644
--- a/docs/building-functions/on_cluster_build.md
+++ b/docs/building-functions/on_cluster_build.md
@@ -2,9 +2,6 @@
 
 This guide describes how you can build a Function on Cluster with Tekton Pipelines. The on cluster build is enabled by fetching Function source code from a remote Git repository. Buildpacks or S2I builder strategy can be used to build the Function image.
 
-> **Note**
-> Not all runtimes support on cluster builds. **Go** and **Rust** are not currently supported.
-
 ## Prerequisite
 1. Install Tekton Pipelines on the cluster. Please refer to [Tekton Pipelines documentation](https://github.com/tektoncd/pipeline/blob/main/docs/install.md) or run the following command:
 ```bash
@@ -39,8 +36,6 @@ build:
     url: https://github.com/my-repo/my-function.git   # required, git repository with the function source code
     revision: main                                    # optional, git revision to be used (branch, tag, commit)
     # contextDir: myfunction                          # optional, needed only if the function is not located in the repository root folder
-  # builderImages:                                    # optional, needed only if the runtime is golang
-  #   pack: ghcr.io/boson-project/go-function-builder:tip
   buildpacks: []
   builder: ""
   buildEnvs: []