Branches: start topic branches with a link to them

Like it is done for the rest of the branches.

Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

src/Branches.md

@@ -42,7 +42,7 @@ If you are interested in maintaining a new topic branch, then please [contact us
 
 ### `rust-pci`
 
-This branch is dedicated to PCI-related abstractions, which are used by e.g. the [NVMe driver](NVMe-driver.md).
+[`rust-pci`](https://github.com/Rust-for-Linux/linux/tree/rust-pci) is dedicated to PCI-related abstractions, which are used by e.g. the [NVMe driver](NVMe-driver.md).
 
 The branch is kept in a compilable state (rebased regularly on top of `rust-next` or mainline). Fixes and features are welcome.