Clarify which yq to use for end-to-end tests

There are two projects with the name "yq" and it's easy to confuse them.
Document which project to use as they are not interchangeable and
e2e-tests do not work if the wrong project is installed.

Signed-off-by: javex <[email protected]>

Author: Javex

README.md

@@ -43,7 +43,7 @@ To run the end-to-end test (e.g. `make e2e-test`), you additionally need:
 
 - `helm` (version 3)
 - `jq`
-- `yq`
+- `yq` (make sure to use [mikefarah/yq](https://github.com/mikefarah/yq) and not [kislyuk/yq](https://github.com/kislyuk/yq))
 - `node` and `npm`
 - `bash` (installed, doesn't have to be your default shell)
 - `base64`