fixes typo and missing script in CONTRIBUTING.md (#477)

Doesn't seem to be a lint script / tool at the moment and I fixed some typos / links whilst here.

CONTRIBUTING.md

@@ -3,7 +3,7 @@
 
 Interested in contributing? We'd love your help! 
 
-Our [issue tracker](https://github.com/pikapkg/snowpack/issues) is always organized with a selection of high-proirity bugs, feature requests, and "help wanted!"/"good first issue" items. For general package troubleshooting and discussions, check out our [Package Community](https://www.pika.dev/npm/snowpack/discuss) discussion board.
+Our [issue tracker](https://github.com/pikapkg/snowpack/issues) is always organized with a selection of high-priority bugs, feature requests, and ["help wanted!"](https://github.com/pikapkg/snowpack/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22)/["good first issue"](https://github.com/pikapkg/snowpack/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) items. For general package troubleshooting and discussions, check out our [Package Community](https://www.pika.dev/npm/snowpack/discuss) discussion board.
 
 ```bash
 # Local Setup
@@ -19,7 +19,6 @@ npm run build
 ```bash
 # Check formatting after changed
 npm run format
-npm run lint
 ```
 
 ```bash