rm plural

README.md

@@ -70,7 +70,7 @@ The most recently selected versions are presented at the top of the dropdown.
 2. For example, `tfswitch -l` or `tfswitch --list-all` to see all versions.
 3. Hit **Enter** to select the desired version.
 
-### Use environment variables
+### Use environment variable
 You can also set the `TF_VERSION` environment version to your desired terraform version. 
 For example:   
 ```bash