docs: community examples (#341)

* docs: community examples section; guidelines doc

* docs(guidelines): one example per repo

Author: alexcg1

Diff for: README.md

@@ -82,7 +82,7 @@ To learn more about how to use Jina, please refer to [our docs](http://www.jina.
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-## 🕊️  Advanced Examples
+## 🚀  Advanced Examples
 
 <table>
   <tr>
@@ -123,6 +123,22 @@ To learn more about how to use Jina, please refer to [our docs](http://www.jina.
   </tr>
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+## Community Examples
+
+Want to add your own example? Please check our [guidelines](example-guidelines.md)!
+
+<table>
+  <tr>
+    <td>
+      <h1>📄</h1>
+    </td>
+    <td>
+      <h4><a href="https://github.com/alexcg1/jina-wikipedia-sentences">Simple Wikipedia Sentence Search</a></h4>
+      Simple Jina app to search sentences from Wikipedia using Transformers
+    </td>
+  </tr>
+</table>
+
 ## Adding Tests for Examples
 
 You are highly encouraged to add a test for your example so that we will be alerted if it breaks in the future:

Diff for: example-guidelines.md

@@ -0,0 +1,63 @@
+# Submit Your Community Example!
+
+Thanks for your interest in submitting your example! Here are some rules and guidelines:
+
+## Rules
+
+### `jina` in `requirements.txt`
+
+To be eligible for listing, you **must** have `jina==x.x.x` in your `requirements.txt`, where `x.x.x` refers to the semantic version number.
+
+Note: If you're building a front-end that just interfaces with Jina's API and doesn't rely on Jina core itself, there's no need to follow this requirement.
+
+### `jina-` at start of name
+
+Your repo name should be `jina-xxxxxxx`.
+
+### Clear README
+
+- Explain what your example does and how to run it
+
+### Use scripts to get external resources
+
+- **For datasets:** Use a script named `get_data.sh`
+- **For models**: If you use an externally-hosted model, call your script `get_model.sh` or similar
+- **For other assets:** Follow the `get_xxx.sh` pattern
+
+### `.gitignore` and `.dockerignore`
+
+Have a `.gitignore` file and list any directories that should be ignored. The same goes for `.dockerignore` if you have `Dockerfile`:
+
+- `data` directory
+- `workspace` directory
+- virtual environment directories
+- directories that store assets retrieved by [scripts](#use-scripts-to-get-external-resources)
+
+### License
+
+You **must** use an open-source license, specified in `LICENSE` in the root of your repo
+
+## Guidelines
+
+We're more easy-going on these
+
+### One Example Per Repo
+
+To make code more maintainable and easier for end users, please include one example per repo.
+
+### Tests
+
+Please include tests to ensure your app or Pod works correctly.
+
+### File Structure
+
+- Please follow the file structure as created by `jina hub new --type app`
+- Store data in `data` and externally-downloaded models in `models`
+
+### Dockerfile
+
+We highly encourage you to add a `Dockerfile`.
+
+### Docker image
+
+For self-contained apps, we would love to host a Docker image on [Jina Hub](https://github.com/jina-ai/jina-hub)