chore: improve formatting in README files for better readability

Author: ryan-gang

README.md

@@ -4,5 +4,6 @@ Content for the "Shell" challenge
 
 ## Setup
 
-This challenge is developed using https://github.com/codecrafters-io/course-sdk. Read the README there for information
-on how to contribute language support & submit solutions.
+This challenge is developed using https://github.com/codecrafters-io/course-sdk.
+Read the README there for information on how to contribute language support &
+submit solutions.

starter_templates/all/code/README.md

@@ -3,14 +3,19 @@
 This is a starting point for {{language_name}} solutions to the
 ["Build Your Own Shell" Challenge](https://app.codecrafters.io/courses/shell/overview).
 
-In this challenge, you'll build your own POSIX compliant shell that's capable of interpreting shell commands, running external programs and builtin commands like cd, pwd, echo and more. Along the way, you'll learn about shell command parsing, REPLs, builtin commands, and more.
+In this challenge, you'll build your own POSIX compliant shell that's capable of
+interpreting shell commands, running external programs and builtin commands like
+cd, pwd, echo and more. Along the way, you'll learn about shell command parsing,
+REPLs, builtin commands, and more.
 
-**Note**: If you're viewing this repo on GitHub, head over to [codecrafters.io](https://codecrafters.io) to try the challenge.
+**Note**: If you're viewing this repo on GitHub, head over to
+[codecrafters.io](https://codecrafters.io) to try the challenge.
 
 # Passing the first stage
 
-The entry point for your `shell` implementation is in `{{ user_editable_file }}`. Study and uncomment the relevant code, and
-push your changes to pass the first stage:
+The entry point for your `shell` implementation is in
+`{{ user_editable_file }}`. Study and uncomment the relevant code, and push your
+changes to pass the first stage:
 
 ```sh
 git commit -am "pass 1st stage" # any msg