Revise contributors guide (sigp#5720)

* Revise contributors guide.

CONTRIBUTING.md

@@ -1,12 +1,14 @@
 # Contributors Guide
+
 [![GitPOAP badge](https://public-api.gitpoap.io/v1/repo/sigp/lighthouse/badge)](https://www.gitpoap.io/gh/sigp/lighthouse)
 
-Lighthouse is an open-source Ethereum 2.0 client. We're community driven and
+Lighthouse is an open-source Ethereum consensus client. We're community driven and
 welcome all contribution. We aim to provide a constructive, respectful and fun
 environment for collaboration.
 
-We are active contributors to the [Ethereum 2.0 specification](https://github.com/ethereum/eth2.0-specs) and attend all [Eth
-2.0 implementers calls](https://github.com/ethereum/eth2.0-pm).
+We are active contributors to
+the [Ethereum Proof-of-Stake Consensus specification](https://github.com/ethereum/consensus-specs) and attend
+all [Ethereum implementers calls](https://github.com/ethereum/pm/).
 
 This guide is geared towards beginners. If you're an open-source veteran feel
 free to just skim this document and get straight into crushing issues.
@@ -41,21 +43,21 @@ We recommend the following work-flow for contributors:
 
 1. **Find an issue** to work on, either because it's interesting or suitable to
    your skill-set. Use comments to communicate your intentions and ask
-questions.
+   questions.
 2. **Work in a feature branch** of your personal fork
    (github.com/YOUR_NAME/lighthouse) of the main repository
    (github.com/sigp/lighthouse).
 3. Once you feel you have addressed the issue, **create a pull-request** with
    `unstable` as the base branch to merge your changes into the main repository.
 4. Wait for the repository maintainers to **review your changes** to ensure the
    issue is addressed satisfactorily. Optionally, mention your PR on
-[discord](https://discord.gg/cyAszAh).
+   [discord](https://discord.gg/cyAszAh).
 5. If the issue is addressed the repository maintainers will **merge your
    pull-request** and you'll be an official contributor!
 
 Generally, you find an issue you'd like to work on and announce your intentions
 to start work in a comment on the issue. Then, do your work on a separate
-branch (a "feature branch") in your own fork of the main repository.  Once
+branch (a "feature branch") in your own fork of the main repository. Once
 you're happy and you think the issue has been addressed, create a pull request
 into the main repository.
 
@@ -66,18 +68,20 @@ steps:
 
 1. [Create a
    fork](https://help.github.com/articles/fork-a-repo/#fork-an-example-repository)
-and [clone
-it](https://help.github.com/articles/fork-a-repo/#step-2-create-a-local-clone-of-your-fork)
-to your local machine.
+   and [clone
+   it](https://help.github.com/articles/fork-a-repo/#step-2-create-a-local-clone-of-your-fork)
+   to your local machine.
 2. [Add an _"upstream"_
    branch](https://help.github.com/articles/fork-a-repo/#step-3-configure-git-to-sync-your-fork-with-the-original-spoon-knife-repository)
-that tracks github.com/sigp/lighthouse using `$ git remote add upstream
-https://github.com/sigp/lighthouse.git` (pro-tip: [use SSH](https://help.github.com/articles/connecting-to-github-with-ssh/) instead of HTTPS).
+   that tracks github.com/sigp/lighthouse using `$ git remote add upstream
+   https://github.com/sigp/lighthouse.git` (
+   pro-tip: [use SSH](https://help.github.com/articles/connecting-to-github-with-ssh/) instead of HTTPS).
 3. Create a new feature branch with `$ git checkout -b your_feature_name`. The
    name of your branch isn't critical but it should be short and instructive.
-E.g., if you're fixing a bug with serialization, you could name your branch
-`fix_serialization_bug`.
-4. Make sure you sign your commits. See [relevant doc](https://help.github.com/en/github/authenticating-to-github/about-commit-signature-verification).
+   E.g., if you're fixing a bug with serialization, you could name your branch
+   `fix_serialization_bug`.
+4. Make sure you sign your commits.
+   See [relevant doc](https://help.github.com/en/github/authenticating-to-github/about-commit-signature-verification).
 5. Commit your changes and push them to your fork with `$ git push origin
    your_feature_name`.
 6. Go to your fork on github.com and use the web interface to create a pull
@@ -92,22 +96,28 @@ by Rob Allen that provides much more detail on each of these steps, if you're
 having trouble. As always, jump on [discord](https://discord.gg/cyAszAh)
 if you get stuck.
 
+Additionally,
+the ["Contributing to Lighthouse" section](https://lighthouse-book.sigmaprime.io/contributing.html#contributing-to-lighthouse)
+of the Lighthouse Book provides more details on the setup.
 
 ## FAQs
 
 ### I don't think I have anything to add
 
 There's lots to be done and there's all sorts of tasks. You can do anything
-from correcting typos through to writing core consensus code. If you reach out,
+from enhancing documentation through to writing core consensus code. If you reach out,
 we'll include you.
 
+Please note, to maintain project quality, we may not accept PRs for small typos or changes
+with minimal impact.
+
 ### I'm not sure my Rust is good enough
 
 We're open to developers of all levels. If you create a PR and your code
 doesn't meet our standards, we'll help you fix it and we'll share the reasoning
 with you. Contributing to open-source is a great way to learn.
 
-### I'm not sure I know enough about Ethereum 2.0
+### I'm not sure I know enough about Ethereum
 
 No problems, there's plenty of tasks that don't require extensive Ethereum
 knowledge. You can learn about Ethereum as you go.