Trivial fixes (#586)

* fix: remove

* fix: add hyper link for exclusive-tests

content/courses/program-optimization/program-architecture.md

@@ -929,7 +929,7 @@ Each concept has an accompanying program and test file. For example, the
 
 **program -** `programs/architecture/src/concepts/sizes.rs`
 
-**test -** `cd tests/sizes.ts`
+**test -** `tests/sizes.ts`
 
 Now that you've read about each of these concepts, feel free to jump into the
 code to experiment a little. You can change existing values, try to break the
@@ -940,7 +940,8 @@ You can fork and/or clone
 to get started. Before building and running the test suite, remember to update
 the `lib.rs` and `Anchor.toml` with your local program ID.
 
-You can run the entire test suite or add `.only` to the `describe` call in a
+You can run the entire test suite or
+[add `.only` to the `describe` call](https://mochajs.org/#exclusive-tests) in a
 specific test file to only run that file's tests. Feel free to customize it and
 make it your own.