Add "before getting started" section to contributing guide

[lrapoport-cf]

What this PR solves / how to test

Fixes N/A.
This PR adds a section to the contributing guide on what you should do before getting started.

Author has addressed the following

• Tests
  • TODO (before merge)
  • Included
  • Not necessary because: only adding to contributing guide
• Changeset (Changeset guidelines)
  • TODO (before merge)
  • Included
  • Not necessary because: only adding to contributing guide
• Public documentation
  • TODO (before merge)
  • Cloudflare docs PR(s): https://github.com/cloudflare/cloudflare-docs/pull/...
  • Not necessary because: only adding to contributing guide, which itself serves as the documentation

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1b234b3

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[github-actions]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-wrangler-5142

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/5142/npm-package-wrangler-5142

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-wrangler-5142 dev path/to/script.js

Additional artifacts:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-create-cloudflare-5142 --no-auto-update

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-cloudflare-kv-asset-handler-5142

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-miniflare-5142

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-cloudflare-pages-shared-5142

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8150348417/npm-package-cloudflare-vitest-pool-workers-5142

Note that these links will no longer work once the GitHub Actions artifact expires.

---

wrangler@3.30.1 includes the following runtime dependencies:

Package	Constraint	Resolved
miniflare	workspace:*	3.20240223.0
workerd	1.20240223.1	1.20240223.1
workerd --version	1.20240223.1	2024-02-23

Please ensure constraints are pinned, and miniflare/workerd minor versions match.

[admah]

@lrapoport-cf is this ready for review?

[lrapoport-cf]

@admah yep it is now :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.36%. Comparing base (040be5d) to head (1b234b3).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5142      +/-   ##
==========================================
+ Coverage   70.31%   70.36%   +0.04%     
==========================================
  Files         298      298              
  Lines       15551    15551              
  Branches     4001     4001              
==========================================
+ Hits        10935    10942       +7     
+ Misses       4616     4609       -7     

see 6 files with indirect coverage changes