Add CONTRIBUTING.md (#44)

* Add CONTRIBUTING.md

* fixes

* add link to README

* more notes

* Apply suggestions from code review

Co-authored-by: Veronica Andreo <[email protected]>

---------

Co-authored-by: Veronica Andreo <[email protected]>

Author: petrasovaa

CONTRIBUTING.md

@@ -0,0 +1,138 @@
+# Contributing to GRASS tutorials
+
+We welcome various contributions — fixing a typo, improving clarity, or adding a new tutorial.  
+Not sure where to begin? [Open an issue](https://github.com/OSGeo/grass-tutorials/issues) to start a conversation.
+
+---
+
+## Getting started
+
+1. **Fork and clone** the repository. Then follow the
+[GitHub guide](https://grass.osgeo.org/grass-devel/manuals/github_guide.html) for the GRASS repository and adjust the workflow for this repository.
+
+2. **Install Quarto** (if you haven’t already), see <https://quarto.org/docs/get-started/>
+
+3. **Preview the site locally:**
+
+    ```sh
+    quarto preview
+    ```
+
+    This launches a local server and opens a live preview in your browser.
+
+4. **Create or edit tutorials:**
+
+    Tutorials are written in Markdown (.qmd) with YAML front matter.
+
+    Add your tutorial to the appropriate section (e.g., ./content/tutorials/mytutorials).
+
+## Writing a tutorial
+
+Give your audience some context, for example include what topics does
+the tutorial cover, what are the prerequisites, and so on.
+
+Use Quarto's [guide](https://quarto.org/docs/guide/) to learn how to write
+Quarto documents and learn [Markdown syntax](https://quarto.org/docs/authoring/markdown-basics.html).
+
+For example, include GRASS commands in fenced code blocks:
+
+```` markdown
+```{python}
+gs.run_command("g.region", raster="elevation")
+```
+````
+
+You can use [tabsets](https://quarto.org/docs/output-formats/html-basics.html#tabsets)
+to show how to run GRASS commands in command line and in Python:
+
+```` markdown
+::: {.panel-tabset group="language"}
+
+## Command line
+
+```{bash}
+g.region raster=elevation
+```
+
+## Python
+
+```{python}
+gs.run_command("g.region", raster="elevation")
+```
+
+:::
+````
+
+Display notes:
+
+``` markdown
+::: {.callout-note title="Setup"}  
+To run this tutorial locally ...  
+:::
+```
+
+## YAML metadata example
+
+Each tutorial must begin with YAML metadata like this:
+
+```` yaml
+---
+title: "Computing slope from elevation data in Python"
+author: "Your Name"
+date: "2025-05-15"
+description: "Learn how to derive slope from elevation data in GRASS in a Jupyter Notebook."
+categories: ["beginner", "geomorphometry", Python]
+thumbnail: slope_thumbnail.webp
+format:
+  ipynb: default
+  html:
+    toc: true
+    code-tools: true
+    code-copy: true
+    code-fold: false
+engine: jupyter
+execute:
+  eval: false
+jupyter: python3
+---
+
+````
+
+Notes:
+
+- Use appropriate categories (tags), include whether the tutorial is for *beginner*, *intermediate*, or *advanced* users.
+
+- Use `eval: false` so that Quarto doesn't run the code during building of the website.
+
+- Specifying format `ipynb: default` will create a Jupyter notebook during the build process and link it from the tutorial page.
+
+## Images
+
+Beautiful images and graphics make tutorials stand out!
+Make sure the images have *sufficient resolution*.
+At the same time, their size should not be too big to load quickly, try to keep it under 200 KB or so. We recommend using *webp* format.
+
+``` markdown
+![Slope map](slope.webp)
+```
+
+Each tutorial needs to have at least one image that can be used on the main page as a thumbnail.
+You can either specify it in the YAML header (`thumbnail: image.webp`) or add `{.preview-image}` to the image.
+
+``` markdown
+![Slope map](slope.webp){.preview-image}
+```
+
+## Submitting your contribution
+
+Check your markdown with a [linter](https://dlaa.me/markdownlint/) and fix as many issues as you can. This will help keeping the tutorials consistent.
+
+Follow the [GitHub guide](https://grass.osgeo.org/grass-devel/manuals/github_guide.html)
+(adapt it to this repo) to submit your tutorial.
+You should **only commit the .qmd file and images**. 
+Once you sumbmit a PR, the CI pipeline will build your
+tutorial, so you and a reviewer can check if everything is ok.
+When a reviewer approves, your PR will be merged soon.
+
+---
+Thanks for helping us build better educational resources for the GRASS community!

README.md

@@ -16,6 +16,8 @@ explained in the [GitHub
 guide](https://github.com/OSGeo/grass/blob/main/doc/development/github_guide.md)
 written for OSGeo/grass repository, so just adjust it for this repository.
 
+See [CONTRIBUTING.md](CONTRIBUTING.md) for more details.
+
 ## License
 
 The content in this repository is dual-licensed under the