docs: improve language in chromium section (#2889)

I asked Gemini to review the English for inconsistencies and grammar
mistakes. This is the result and I hope it's useful!

As a non-native speaker, it is hard for me to evaluate the finer
details, so let me know if you would like to see changes (or even
better: make them directly in the PR with the suggestion function).

---------

Co-authored-by: Dmitri Gribenko <gribozavr@gmail.com>

src/chromium/cargo.md

@@ -60,8 +60,8 @@ may offer an advantage"):
 
   - Perhaps surprisingly, Rust is becoming increasingly popular in the industry
     for writing command line tools. The breadth and ergonomics of libraries is
-    comparable to Python, while being more robust (thanks to the rich
-    typesystem) and running faster (as a compiled, rather than interpreted
+    comparable to Python, while being more robust (thanks to the rich type
+    system) and running faster (as a compiled, rather than interpreted
     language).
   - Participating in the Rust ecosystem requires using standard Rust tools like
     Cargo. Libraries that want to get external contributions, and want to be

src/chromium/setup.md

@@ -22,7 +22,7 @@ It's also recommended that you have Visual Studio code installed.
 
 # About the exercises
 
-This part of the course has a series of exercises which build on each other.
+This part of the course has a series of exercises that build on each other.
 We'll be doing them spread throughout the course instead of just at the end. If
 you don't have time to complete a certain part, don't worry: you can catch up in
 the next slot.

src/chromium/testing.md

@@ -44,9 +44,9 @@ used:
   the C++ and the Rust implementation (parameterizing the tests so they enable
   or disable Rust using a `ScopedFeatureList`).
 
-- Hypothetical/WIP PNG integration may need to implement memory-safe
-  implementation of pixel transformations that are provided by `libpng` but
-  missing in the `png` crate - e.g. RGBA => BGRA, or gamma correction. Such
-  functionality may benefit from separate tests authored in Rust.
+- Hypothetical/WIP PNG integration may need memory-safe implementations of pixel
+  transformations that are provided by `libpng` but missing in the `png` crate -
+  e.g. RGBA => BGRA, or gamma correction. Such functionality may benefit from
+  separate tests authored in Rust.
 
 </details>