Merge pull request #9042 from priyansh17/readme-update/test

[Readme update] Add image registry proxy option to E2E test configuration

Author: blackpiglet

test/e2e/README.md

@@ -80,6 +80,7 @@ These configuration parameters are expected as values to the following command l
 1. `--fail-fast`: A switch for for failing fast on meeting error.
 1. `--has-vsphere-plugin`: A switch to indicate whether the Velero vSphere plugin is installed for vSphere environment.
 1. `--worker-os`: A switch to indicate the workload should be ran on windows or linux OS.
+1. `--image-registry-proxy`: specifies a custom image registry proxy to be used for pulling container images.
 
 These configurations or parameters are used to generate install options for Velero for each test suite.
 
@@ -133,8 +134,7 @@ Below is a mapping between `make` variables to E2E configuration flags.
 1. `FAIL_FAST`: `--fail-fast`. Optional.
 1. `HAS_VSPHERE_PLUGIN`: `--has-vsphere-plugin`. Optional.
 1. `WORKER_OS`: `--worker-os`. Optional.
-
-
+1. `IMAGE_REGISTRY_PROXY`: `--image-registry-proxy.` Optional.
 
 ### Examples