Update README.md to include how to remove ^M (#1220)

At least for me every time I download the file I have to remove the ^M from each line in the file.  I have found sed is the easiest way.

README.md

@@ -180,8 +180,9 @@ To save updates and make changes to appointed users for early testing of the Tig
 2. Save those updated changes
 3. Download the file as a .CSV file
 4. Copy the downloaded .CSV file to `data` > `user_registration_list.csv`
-5. Open a PR to check the updated file into version control
-6. Once that PR is merged, release and deploy the code. This will automatically run the `load_users.rake` rake task.
+5. run SED to remove the ^M from the file `sed -e "s/\r//g" user_registration_list.csv > user_registration_list_production.csv`
+6. Open a PR to check the updated file into version control
+7. Once that PR is merged, release and deploy the code. This will automatically run the `load_users.rake` rake task.
 
 ## Sidekiq
 
@@ -206,4 +207,4 @@ Workers must be running on each server in order for mail to be sent and backgrou
 
  To demonstrate the look and feel of elements defined as part of the style guide, this application includes a "styles preview" page, visible at the path `/styles_preview`.  It is intended as a place to make CSS and HTML attributes available for review by users either before they are implemented in the UI, or are difficult to access within the UI of the rest of the application, but the look and feel must be reviewed.  See [this ticket](https://github.com/pulibrary/tigerdata-app/issues/1000) as an example of CSS that is also added to the Styles Preview page as part of development.
 
- All elements on the Styles Preview page are added manually during feature development, and only need to be added if they match the criteria described above (either not yet in the UI or difficult to access otherwise within the UI).  It can be edited at [`app/views/welcome/styles_preview.html.erb`](https://github.com/pulibrary/tigerdata-app/blob/main/app/views/welcome/styles_preview.html.erb).
+ All elements on the Styles Preview page are added manually during feature development, and only need to be added if they match the criteria described above (either not yet in the UI or difficult to access otherwise within the UI).  It can be edited at [`app/views/welcome/styles_preview.html.erb`](https://github.com/pulibrary/tigerdata-app/blob/main/app/views/welcome/styles_preview.html.erb).