clarify something in step 1

.github/steps/1-remove-env-file.md

@@ -11,11 +11,11 @@
 
 _Welcome to "Change commit history"! :wave:_
 
-`.env` files usually contain sensitive content. For this course, we'll work on removing that file and all traces in the Git history. The first step is to remove the file from repository. We'll alter the history later.
+We'll start by working with `.env` files. These files usually contain sensitive content. For this course, we'll work on removing that file and all traces in the Git history. The first step is to remove the file from repository. We'll alter the history later.
 
 We'll assume you're using the command line, but you can complete the course using your preferred tooling.
 
-**What is _sensitive content_?** Sensitive content is anything that is checked into your repository history that may put you or your organization at risk. This content usually comes in the form of credentials (i.e., passwords, access keys). Simply deleting the content from the root direcotry isn't enough since Git keeps copies of every change that it's ever tracked in its history, but we'll start there.
+**What is _sensitive content_?** Sensitive content is anything that is checked into your repository history that may put you or your organization at risk. This content usually comes in the form of credentials (i.e., passwords, access keys). The best practice for accidentally exposed sensitive content is to invalidate it (i.e., revoke a personal access token), completely remove it from all repository copies, and take measures to prevent future exposure.
 
 See [Deleting a file on GitHub Docs](https://docs.github.com/en/repositories/working-with-files/managing-files/deleting-files-in-a-repository#deleting-a-file) if you need additional help removing a file.