Past branches: remove links to recently deleted branches

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

Author: ojeda

src/Past-branches.md

@@ -36,13 +36,13 @@ Changes to these branches landed via GitHub PRs. Nevertheless, contributions sho
 
 ### `staging/dev`
 
-[`staging/dev`](https://github.com/Rust-for-Linux/linux/tree/staging/dev) was a branch intended to integrate the other topic branches (similar to the role of `rust-dev` for the main branches).
+`staging/dev` was a branch intended to integrate the other topic branches (similar to the role of `rust-dev` for the main branches).
 
 It was maintained by Danilo Krummrich and Philipp Stanner. You could contact them through [Zulip](Contact.md#zulip-chat).
 
 ### `staging/rust-device`
 
-[`staging/rust-device`](https://github.com/Rust-for-Linux/linux/tree/staging/rust-device) was dedicated to device/driver-related abstractions.
+`staging/rust-device` was dedicated to device/driver-related abstractions.
 
 The branch was kept in a compilable state (rebased regularly on top of `rust-next` or mainline). Fixes and features were welcome.
 
@@ -58,7 +58,7 @@ It was maintained by Trevor Gross and Valentin Obst. You could contact them thro
 
 ### `staging/rust-pci`
 
-[`staging/rust-pci`](https://github.com/Rust-for-Linux/linux/tree/staging/rust-pci) was dedicated to PCI-related abstractions, which were used by e.g. the [NVMe driver](NVMe-driver.md).
+`staging/rust-pci` was dedicated to PCI-related abstractions, which were used by e.g. the [NVMe driver](NVMe-driver.md).
 
 The branch was kept in a compilable state (rebased regularly on top of `rust-next` or mainline). Fixes and features were welcome.