doc: add ci-cd folder and add github-actions to the folder (#1326)

Author: Killpit

src/ci-cd/github-actions.md

@@ -0,0 +1,104 @@
+# Overview of `foundry-toolchain`
+
+`foundry-toolchain` can be used to install Foundry for GitHub Actions build processes.
+
+### Example workflow
+
+```
+on: [push]
+
+name: test
+
+jobs:
+  check:
+    name: Foundry project
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          submodules: recursive
+
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
+
+      - name: Run tests
+        run: forge test -vvv
+
+      - name: Run snapshot
+        run: forge snapshot
+```
+
+### Inputs
+
+| Name | Required | Default | Description | Type |
+|---|---|---|---|---|
+| cache | No | true | Whether to cache RPC responses or not. | bool |
+| version | No | nightly | Version to install, e.g. nightly or 1.8.8. Note: Foundry only has nightly builds for the time being. | string |
+| cache-key | No | `${{ github.job }}` | The cache key to use for caching. | string |
+| cache-restore-keys | No | `[${{ github.job }}]` | The cache keys to use for restoring the cache. | string[] |
+
+### RPC Caching
+
+By default, this action matches Forge's behavior and caches all RPC responses in the `~/.foundry/cache/rpc` directory. This is done to speed up the tests and avoid hitting the rate limit of your RPC provider.
+
+The logic of the caching is as follows:
+
+- Always load the latest valid cache, and always create a new one with the updated cache.
+- When there are no changes to the fork tests, the cache does not change but the key does, since the key is based on the commit hash.
+- When the fork tests are changed, both the cache and the key are updated.
+
+If you would like to disable the caching (e.g. because you want to implement your own caching mechanism), you can set the `cache` input to `false`, like this:
+
+```
+- name: Install Foundry
+  uses: foundry-rs/foundry-toolchain@v1
+  with:
+    cache: false
+```
+
+### Custom Cache Keys
+
+You have the ability to define custom cache keys by utilizing the `cache-key` and `cache-restore-keys` inputs. This feature is particularly beneficial when you aim to tailor the cache-sharing strategy across multiple jobs. It is important to ensure that the cache-key is unique for each execution to prevent conflicts and guarantee successful cache saving.
+
+For instance, if you wish to utilize a shared cache between two distinct jobs, the following configuration can be applied:
+
+```
+- name: Install Foundry
+  uses: foundry-rs/foundry-toolchain@v1
+  with:
+    cache-key: custom-seed-test-${{ github.sha }}
+    cache-restore-keys: |-
+      custom-seed-test-
+      custom-seed-
+---
+- name: Install Foundry
+  uses: foundry-rs/foundry-toolchain@v1
+  with:
+    cache-key: custom-seed-coverage-${{ github.sha }}
+    cache-restore-keys: |-
+      custom-seed-coverage-
+      custom-seed-
+```
+
+#### Deleting Caches
+
+You can delete caches via the GitHub Actions user interface. Just go to your repo's "Actions" page:
+
+`https://github.com/<OWNER>/<REPO>/actions/caches`
+
+Then, locate the "Management" section, and click on "Caches". You will see a list of all of your current caches, which you can delete by clicking on the trash icon.
+
+#### Fuzzing
+
+Note that if you are fuzzing in your fork tests, the RPC cache strategy above will not work unless you set a [fuzz seed](https://book.getfoundry.sh/reference/config/testing#seed). You might also want to reduce your number of RPC calls by using [Multicall](https://github.com/mds1/multicall).
+
+### Summaries
+
+You can add the output of Forge and Cast commands to GitHub step summaries. The summaries support GitHub flavored Markdown.
+
+For example, to add the output of `forge snapshot` to a summary, you would change the snapshot step to:
+
+```
+- name: Run snapshot
+  run: NO_COLOR=1 forge snapshot >> $GITHUB_STEP_SUMMARY
+```