add pull_request trigger and update add note on fail case

Author: SamMorrowDrums

src/doc/src/guide/continuous-integration.md

@@ -30,6 +30,10 @@ name: Cargo Build & Test
 
 on:
   push:
+  pull_request:
+
+env: 
+  CARGO_TERM_COLOR: always
 
 jobs:
   build_and_test:
@@ -46,9 +50,10 @@ jobs:
       - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
       - run: cargo build --verbose
       - run: cargo test --verbose
+  
 ```
 
-This will test all three release channels. You can also click `"Actions" > "new workflow"` in the GitHub UI and select Rust to add the [default configuration](https://github.com/actions/starter-workflows/blob/main/ci/rust.yml) to your repo. See [GitHub Actions documentation](https://docs.github.com/en/actions) for more information.
+This will test all three release channels (note a failure in any toolchain version will fail the entire job). You can also click `"Actions" > "new workflow"` in the GitHub UI and select Rust to add the [default configuration](https://github.com/actions/starter-workflows/blob/main/ci/rust.yml) to your repo. See [GitHub Actions documentation](https://docs.github.com/en/actions) for more information.
 
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