docs: improve contributing guidelines (#8166)

docs/contributing/README.md

@@ -8,7 +8,8 @@ It should be considered a map to help you navigate the process.
 If you are unsure where to begin, use the following guides:
 
 - Want to report or triage a bug? Start with [Contributing in Issues](contributing-in-issues.md).
-- Looking for something to work on? Filter issues by [`E-help-wanted`](https://github.com/tokio-rs/tokio/labels/E-help-wanted).
+- Looking for something to work on? Check the open [`issues`](https://github.com/tokio-rs/tokio/issues)
+(some might be in progress or still under discussion, so leave a comment before starting the work).
 - Planning to submit a PR? Read [Pull Requests](pull-requests.md) for the full workflow and required checks.
 - Want to understand what the labels on issues mean? See [Keeping track of issues and PRs](keeping-track-of-issues-and-prs.md).
 - Interested in code review? See [Reviewing Pull Requests](reviewing-pull-requests.md).
@@ -22,7 +23,7 @@ If you are unsure where to begin, use the following guides:
     - [Resolving a Bug Report](contributing-in-issues.md#resolving-a-bug-report)
 - [Pull Requests](pull-requests.md)
     - [Cargo Commands](pull-requests.md#cargo-commands)
-    - [Performing spellcheck on tokio codebase](pull-requests.md#performing-spellcheck-on-tokio-codebase)
+    - [Performing spellcheck on Tokio codebase](pull-requests.md#performing-spellcheck-on-tokio-codebase)
     - [Tests](pull-requests.md#tests)
         - [Integration tests](pull-requests.md#integration-tests)
         - [Fuzz tests](pull-requests.md#fuzz-tests)

docs/contributing/keeping-track-of-issues-and-prs.md

@@ -81,8 +81,10 @@ The module label provides a more fine grained categorization than **Area**.
 Some extra information.
 
 - **T-docs** This is about documentation.
+- **T-io-uring** This is about io-uring (Linux).
 - **T-performance** This is about performance.
 - **T-v0.1.x** This is about old Tokio.
+- **T-wasm** This is about Web Assembly.
 
 Any label not listed here is not in active use.
 

docs/contributing/pull-requests.md

@@ -4,10 +4,12 @@ Pull Requests are the way concrete changes are made to the code, documentation,
 and dependencies in the Tokio repository.
 
 Even tiny pull requests (e.g., one-character pull request fixing a typo in API
-documentation) are greatly appreciated. Before making a large change, it is
-usually a good idea to first open an issue describing the change to solicit
-feedback and guidance. This will increase the likelihood of the PR getting
-merged.
+documentation) are greatly appreciated.
+
+> [!NOTE]
+> Before making a large change, it is usually a good idea to first open an
+> issue describing the change to solicit feedback and guidance.
+> This will increase the likelihood of the PR getting merged.
 
 ### Cargo Commands
 
@@ -23,8 +25,10 @@ cargo check --all-features
 cargo test --all-features
 ```
 
-**NOTE**: there are some features that are not supported in every system, so you might
-need to specify which features you want to pass to cargo (e.g., `cargo check --features=full,io-uring`)
+> [!NOTE]
+> There are some features that are not available in some systems (e.g., `io-uring`
+> which is Linux only). In that case you cannot use the `--all-features` and you
+> should specify only the features that are supported (e.g., `--features=full`).
 
 Ideally, you should use the same version of clippy as the one used in CI
 (defined by `env.rust_clippy` in [ci.yml][ci.yml]), because newer versions
@@ -99,7 +103,7 @@ MIRIFLAGS="-Zmiri-disable-isolation -Zmiri-strict-provenance" \
     cargo +nightly miri test --features full --lib --tests
 ```
 
-### Performing spellcheck on tokio codebase
+### Performing spellcheck on Tokio codebase
 
 You can perform a spell-check on the Tokio codebase. For details of how to use the spellcheck tool, feel free to visit
 https://github.com/drahnr/cargo-spellcheck