docs: update contribution guidelines (#1691)

* docs(contributing): add subheading backend under styling

* docs: add styling for frontend

docs/CONTRIBUTING.md

@@ -1,4 +1,3 @@
-
 # Contributing
 
 ## Requirements
@@ -16,7 +15,9 @@ Use the following `make` commands and scripts in development:
 
 ## Styling
 
-### Use Go style
+### Backend
+
+#### Use Go style
 
 Contributions must adhere to the guidelines outlined in [Effective
 Go](https://go.dev/doc/effective_go). We prefer linting rules over documenting
@@ -26,13 +27,27 @@ Read [Go's Code Review Comments
 Wiki](https://github.com/golang/go/wiki/CodeReviewComments) for information on
 common comments made during reviews of Go code.
 
-### Avoid unused packages
+#### Avoid unused packages
 
 Coder writes packages that are used during implementation. It isn't easy to
 validate whether an abstraction is valid until it's checked against an
 implementation. This results in a larger changeset, but it provides reviewers
 with a holistic perspective regarding the contribution.
 
+### Frontend
+
+#### Follow component conventions
+
+Each component gets its own folder. Make sure you add a test and Storybook
+stories for the component as well. By keeping these tidy, the codebase will
+remain easy-to-navigate, healthy and maintainable for all contributors.
+
+#### Keep accessibility in mind
+
+We strive to keep our UI accessible. When using colors, avoid adding new
+elements with low color contrast. Always use labels on inputs, not just
+placeholders. These are important for screen-readers.
+
 ## Reviews
 
 > The following information has been borrowed from [Go's review