doc: warn default Docker image has to be changed

README.md

@@ -20,8 +20,8 @@ include:
 The Python template uses some global configuration used throughout all jobs.
 
 | Name                 | description                                                                           | default value      |
-| -------------------- | ---------------------------------------------------------------------------------------------------------------- | ------------------ |
-| `PYTHON_IMAGE`       | The Docker image used to run Python. **It is highly recommended to set the specific version your project needs** | `python:3`    |
+| -------------------- | ------------------------------------------------------------------------------------- | ------------------ |
+| `PYTHON_IMAGE`       | The Docker image used to run Python <br/>:warning: **set the version required by your project** | `python:3`         |
 | `PIP_INDEX_URL`      | Python repository url                                                                 | _none_             |
 | `PYTHON_PROJECT_DIR` | Python project root directory                                                         | `.`                |
 | `REQUIREMENTS_FILE`  | Path to requirements file _(relative to `$PYTHON_PROJECT_DIR`)_                       | `requirements.txt` |
@@ -281,6 +281,6 @@ It is bound to the `publish` stage, applies only on tags and uses the following
 | `DOCS_BUILD_DIR`         | Output build directory for documentation                                               | `public`                          |
 | `DOCS_MAKE_ARGS`         | Args of make command                                                                   | `html BUILDDIR=${DOCS_BUILD_DIR}` |
 
-## Gitlab compatibility
+## GitLab compatibility
 
 :information_source: This template is actually tested and validated on GitLab Community Edition instance version 13.12.11

kicker.json

@@ -6,7 +6,7 @@
   "variables": [
     {
       "name": "PYTHON_IMAGE",
-      "description": "The Docker image used to run Python - **it is highly recommended to set the specific version your project needs**",
+      "description": "The Docker image used to run Python - **set the version required by your project**",
       "default": "python:3"
     },
     {