Add contributing guidelines

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# Contributing to Finnhub-rs
+
+Firstly, thanks for wanting to contribute! All contributions are welcome, whether they are large API design changes, typo fixes, you name it.
+
+## Finding Issues to Work On
+
+You can find issues to work on under the [issues tab](github.com/henryboisdequin/finnhub-rs/issues). I would recommend starting with issues
+labeled under `help-wanted` or `good-first-issue`. You can say you are
+working on an issue by commenting, "I would like to work on this" or
+something along those lines to prevent more than one person working on an
+issue at once.
+
+These issues are also triaged on the [`main` project board](https://github.com/henryboisdequin/finnhub-rs/projects/1). There you will see the issues
+sorted under `Bugs`, `Feature Requests`, and `Good for new Contributors`.
+This makes it slightly easier to keep track on what issues are for what
+purpose and to find them easily.
+
+## Submitting a PR
+
+Once again, all PRs are welcome! Just submit a PR and kindly summarise your
+changes or, if applicable, which issue this PR fixes. For example, if I was
+working on issue `#2`, this would be my PR description: `Fixes #2`.
+
+---
+
+Once again, thanks for considering to contribute to Finnhub-rs. If you
+think this document can be improved, feel free to submit a PR.

README.md

@@ -2,7 +2,7 @@
 
 ![License: MIT](https://img.shields.io/badge/License-MIT-red.svg)
 
-Rust client for the <a href="https://finnhub.io/">Finnhub API</a>. Finnhub is a new Stock API which provides endless data for stocks, currencies, and crypto.
+Rust client for the [Finnhub API](https://finnhub.io/). Finnhub is a new Stock API which provides endless data for stocks, currencies, and crypto.
 
 ## Minimal Example:
 
@@ -19,3 +19,7 @@ fn main() {
     println!("{:#?}", res);
 }
 ```
+
+## Contributing
+
+Thanks for considering to contribute to Finnhub-rs! Please read the contributing guidelines in the [`CONTRIBUTING.md`](https://github.com/henryboisdequin/finnhub-rs/blob/main/CONTRIBUTING.md) to get started.