docs: add submission guidelines for snippets in README

Author: xavwe

README.md

@@ -10,3 +10,26 @@
 - [x] Style Store
 - [x] Search
 
+## Submit your snippet
+To add your plugin to the list, make a pull request to the `snippets.json` file. Please add your snippet to the end of the list.
+
+- `id`: A unique ID for your snippet.
+- `name`: The name of your snippet.
+- `author`: The author's name.
+- `description`: A short description of what your snippet does.
+- `repo`: The GitHub repository identifier, in the form of user-name/repo-name, if your GitHub repo is located at https://github.com/user-name/repo-name.
+- `folder`: The folder name where your snippet is located. This is the folder name inside the repository, not the full path.
+
+Your Repo has to be public, otherwise the snippet will not be installed and has to be in the following structure:
+
+```
+├── folder1
+│   ├── snippet.css
+│   ├── README.md
+└──folder2
+    ├── snippet.css
+    ├── README.md
+
+```
+*Notice that every snippet consists of a `snippet.css` and `README.md` file. The `README.md` file is optional, but it is recommended to add it to provide more information about your snippet. The `snippet.css` file is the actual CSS code that will be applied to your Obsidian vault.*
+