Fix casing of “Rust” (#2433)

src/cargo.md

@@ -23,7 +23,7 @@ auto-completion and jump-to-definition functionality for [VS Code], [Emacs],
 <details>
 
 - On Debian/Ubuntu, you can also install Cargo, the Rust source and the
-  [Rust formatter] via `apt`. However, this gets you an outdated rust version
+  [Rust formatter] via `apt`. However, this gets you an outdated Rust version
   and may lead to unexpected behavior. The command would be:
 
   ```shell

src/modules/filesystem.md

@@ -10,7 +10,7 @@ Omitting the module content will tell Rust to look for it in another file:
 mod garden;
 ```
 
-This tells rust that the `garden` module content is found at `src/garden.rs`.
+This tells Rust that the `garden` module content is found at `src/garden.rs`.
 Similarly, a `garden::vegetables` module can be found at
 `src/garden/vegetables.rs`.