docs: add contributing guide

CONTRIBUTING.md

@@ -0,0 +1,33 @@
+# Contributing to Token.js
+
+Thanks for your interest in improving Token.js!
+
+We appreciate support in the following areas:
+- Reporting issues. If you notice any bugs or have suggestions for new features, please [open an issue](https://github.com/token-js/token.js/issues/new).
+- Fixing and responding to existing issues. You can start off with those tagged ["good first issue"](https://github.com/token-js/token.js/labels/good%20first%20issue), which are meant as introductory issues for external contributors.
+
+## Development Quickstart
+
+### Clone the repo
+
+```bash
+git clone https://github.com/token-js/token-js.git
+```
+
+### Open the project and install the dependencies
+
+```bash
+cd llm && pnpm install
+```
+
+### Test your changes
+
+```bash
+pnpm test
+```
+
+### Run the linter
+
+```bash
+pnpm lint
+```

README.md

@@ -191,31 +191,7 @@ This table provides an overview of the features that Token.js supports from each
 
 ## Contributing
 
-PRs are accepted!
-
-### Clone the repo
-
-```bash
-git clone https://github.com/token-js/token-js.git
-```
-
-### Open the project and install the dependencies
-
-```bash
-cd llm && pnpm install
-```
-
-### Test your changes
-
-```bash
-pnpm test
-```
-
-### Run the linter
-
-```bash
-pnpm lint
-```
+See our [Contributing guide](./CONTRIBUTING.md) to learn how to contribute to Token.js.
 
 ## Contact Us
 

docs/SUMMARY.md

@@ -12,3 +12,4 @@
   * [OpenAI](providers/openai.md)
   * [Perplexity](providers/perplexity.md)
 * [Contact Us](contact-us.md)
+* [Contributing](https://github.com/token-js/token.js/blob/main/CONTRIBUTING.md)