Update contributing.md

Author: behrica

notebooks/contributing.md

@@ -6,5 +6,22 @@
 1. Create a folder in `projects` with a [Clay](https://scicloj.github.io/clay/) notebook, multiple notebooks, or a book. Add a link to the scrapbook at the top of your notebooks. 
 You need to have a `.devcontainer` folder in it.
 
-2. Create a [Pull Request](https://github.com/scicloj/clojure-data-tutorials/pulls) adding it at the bottom of the [table of contents](https://github.com/scicloj/clojure-data-tutorials/blob/main/notebooks/toc.edn).
+2. Create a [Pull Request](https://github.com/scicloj/clojure-data-tutorials/pulls) adding our new folder at the bottom of the [table of contents](https://github.com/scicloj/clojure-data-tutorials/blob/main/notebooks/toc.edn).
+
+You need to specify 
+| tag | example | description|
+|-----|--------| ------- |
+|:created       | "2024-01-11"| creadion date of notebook|
+|:title         | "Machine learning - DRAFT"|title of notebook|
+|:url           |  "projects/noj/ml.html"|  entry point html file of the notebook|
+|:source-path   | "projects/noj/notebooks/ml.clj"| folder or file as entrypoint of the notebook|
+|:folder        |  "projects/noj" | base folder, not needed if :souce path is a folder|
+|:cmd           | "clj notebooks/render.clj" | command to render notebook|
+|:tags          | [:noj :ml :scicloj.ml :draft] | some tags|
+
+If `:source-path` is a folder, `:folder` is not needed
+(A clay notebook can be ither a .clj fil or a folder of .clj files)
+
+`:cmd` need to be a command, which renders your notebook into `docs/` folder
+