Merge pull request opendatahub-io#1011 from jstourac/updates

NO-JIRA: chore - update the default image version in Makefile; add links to our contrib guide

Author: openshift-merge-bot[bot]

CONTRIBUTING.md

@@ -44,6 +44,9 @@ Pull requests are the best way to propose changes to the notebooks repository:
 ### Some basic instructions how to apply the new tests into [openshift-ci](https://github.com/openshift/release)
 
 - Fork the [openshift-ci](https://github.com/openshift/release) repo and create your branch from master.
+  - Definition and configuration of jobs used by this repository is on these places:
+    - [jobs](https://github.com/openshift/release/tree/master/ci-operator/jobs/opendatahub-io/notebooks)
+    - [config](https://github.com/openshift/release/tree/master/ci-operator/config/opendatahub-io/notebooks)
 - Issue a pull request there by adding the following.
 - Get navigated into [opendatahub-io-notebooks-main.yaml](https://github.com/openshift/release/blob/master/ci-operator/config/opendatahub-io/notebooks/opendatahub-io-notebooks-main.yaml) file.
   - Under `images` option, add build instructions (directory path, from(parent image) and to(new notebook name))

Makefile

@@ -19,7 +19,7 @@ endif
 .RECIPEPREFIX =
 
 IMAGE_REGISTRY   ?= quay.io/opendatahub/workbench-images
-RELEASE	 		 ?= 2024b
+RELEASE	 		 ?= 2025a
 RELEASE_PYTHON_VERSION	 ?= 3.11
 # additional user-specified caching parameters for $(CONTAINER_ENGINE) build
 CONTAINER_BUILD_CACHE_ARGS ?= --no-cache
@@ -36,12 +36,6 @@ endif
 DATE 		?= $(shell date +'%Y%m%d')
 WHERE_WHICH ?= which
 
-ifeq ($(RELEASE), 2025a)
-	RELEASE_PYTHON_VERSION = 3.12
-else ifeq ($(RELEASE), 2024a)
-	RELEASE_PYTHON_VERSION = 3.9
-endif
-
 
 # linux/amd64 or darwin/arm64
 OS_ARCH=$(shell go env GOOS)/$(shell go env GOARCH)