chore: update the contribution guidelines (#1987)

* chore: update the contribution guidelines

* move

* note about non-deterministic steps

* little bit of separation

* language nits, add accessibility

* add reasoning

CONTRIBUTING.md

+# Contributing
+
+Thank you for your interest in contributing to the Uniswap interface! 🦄
+
 # Development
 
-## Install Dependencies
+## Running the interface locally
 
-```bash
-yarn install
-```
+1. `yarn install`
+1. `yarn start`
 
-## Generate locale files
+## Creating a production build
 
-```
-yarn i18n:extract
-```
+1. `yarn install`
+1. `yarn build`
 
-## Run the interface
+## Engineering standards
 
-```bash
-yarn start
-```
+Code merged into the `main` branch of this repository should adhere to high standards of correctness and maintainability. 
+Use your best judgment when applying these standards.  If code is in the critical path, will be frequently visited, or 
+makes large architectural changes, consider following all the standards.
 
-# Contributing
+- Have at least one engineer approve of large code refactorings
+- At least manually test small code changes, prefer automated tests
+- Thoroughly unit test when code is not obviously correct
+- Add integration tests for new pages or flows
+- Verify that all CI checks pass before merging
+- Have at least one product manager or designer approve of significant UX changes
 
-Thank you for your interest in contributing to the Uniswap interface! 🦄
+## Guidelines
+
+The following points should help guide your development:
+
+- Security: the interface is safe to use
+  - Avoid adding unnecessary dependencies due to [supply chain risk](https://github.com/LavaMoat/lavamoat#further-reading-on-software-supplychain-security)
+- Reproducibility: anyone can build the interface
+  - Avoid adding steps to the development/build processes
+  - The build must be deterministic, i.e. a particular commit hash always produces the same build
+- Decentralization: anyone can run the interface
+  - An Ethereum node should be the only critical dependency 
+  - All other external dependencies should only enhance the UX ([graceful degradation](https://developer.mozilla.org/en-US/docs/Glossary/Graceful_degradation))
+- Accessibility: anyone can use the interface
+  - The interface should be responsive, small and run well on low performance devices (majority of swaps on mobile!)
 
 ## Finding a first issue
 
 Start with issues with the label
 [`good first issue`](https://github.com/Uniswap/uniswap-interface/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22).
 
-## Pull requests
-
-**Please open all pull requests against the `main` branch.**
-CI checks will run against all PRs.
-
 # Translations
 
 Help Uniswap reach a global audience! 
@@ -40,7 +55,7 @@ Uniswap uses [Crowdin](https://crowdin.com/project/uniswap-interface)
 for managing translations. Whenever a new string is added to the project,
 it gets uploaded to Crowdin for translation by [this workflow](./.github/workflows/crowdin.yaml).
 
-Every hour, translations are synced from Crowdin in [this other workflow](./.github/workflows/crowdin-sync.yaml).
+Every hour, translations are synced from Crowdin to the repository in [this other workflow](./.github/workflows/crowdin-sync.yaml).
 
 You can contribute by joining Crowdin to proofread existing translations [here](https://crowdin.com/project/uniswap-interface/invite?d=93i5n413q403t4g473p443o4c3t2g3s21343u2c3n403l4b3v2735353i4g4k4l4g453j4g4o4j4e4k4b323l4a3h463s4g453q443m4e3t2b303s2a35353l403o443v293e303k4g4n4r4g483i4g4r4j4e4o473i5n4a3t463t4o4)