add README.md (#61)

* add README.md

* add some more info to readme

* Update README.md

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Co-authored-by: Will Winder <[email protected]>

README.md

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+# chainlink-ccip
+
+This is the repo that implements the OCR3 CCIP plugins. This includes the commit and execution plugins.
+
+## Getting Started
+
+### Go Version
+
+This repo uses Go 1.22. You can install Go from their [installation page](https://go.dev/doc/install).
+
+### Running the Linter
+
+We use golangci-lint as our linting tool. Run the linter like this:
+
+```sh
+make lint
+```
+
+### Running the Unit Tests
+
+```sh
+make test
+```
+
+### Generating the Mocks
+
+We use mockery to generate mocks and they're organized in the [mockery.yaml](./.mockery.yaml) file.
+
+```sh
+make generate
+```
+
+## Development Cycle
+
+In order to keep the `ccip-develop` branch in working condition, we need to make sure the integration test
+[written in the CCIP repo](https://github.com/smartcontractkit/ccip/blob/03ae3bbed0e6020be5fa9be26d03af21f152d7dc/core/capabilities/ccip/ccip_integration_tests/ocr3_node_test.go#L37)
+will pass.
+
+As such, part of CI will run this integration test combined with your latest pushed change.
+
+Follow the steps below to ensure that we don't run into any unexpected breakages.
+
+1. Create a PR on chainlink-ccip with the changes you want to make.
+2. CI will run the integration test in the CCIP repo after applying your changes.
+3. If the integration test fails, make sure to fix it first before merging your changes into
+the `ccip-develop` branch of chainlink-ccip. You can do this by:
+    - Creating a branch in the CCIP repo and running `go get github.com/smartcontractkit/chainlink-ccip@<your-branch-commit-sha>`.
+    - Fixing the build/tests.
+4. Once your ccip PR is approved, merge it.
+5. Go back to your chainlink-ccip PR and re-run the integration test workflow.
+6. Once the integration test passes, merge your chainlink-ccip PR into `ccip-develop`, however do not delete the branch on the remote.
+7. Create a new PR in ccip that points to the newly merged commit in the `ccip-develop` tree and merge that.