docs: contributing guidelines (#2860)

Outdated and needs work but will suffice.

Author: iuioiua

.github/CONTRIBUTING.md

@@ -0,0 +1,7 @@
+# Contributing Guidelines
+
+## Submitting a pull request
+
+First, please be sure to
+[install Puppeteer](https://github.com/lucacasonato/deno-puppeteer#installation).
+Then, please ensure `deno task ok` is run and successfully passes.

README.md

@@ -65,7 +65,7 @@ docs.
 ## Contributing
 
 We appreciate your help! To contribute, please read our
-[contributing instructions](https://deno.com/manual/references/contributing#submitting-a-pr-to-fresh).
+[contributing guideline](./.github/CONTRIBUTING.md).
 
 ## Adding your project to the showcase