Add warning about trailing forward slash

learners/migrating-from-styles.md

@@ -14,7 +14,7 @@
 **_We strongly recommend that you create a backup of your lesson repository before you follow this workflow._**
 :::
 
 :::::::: prereqs 
 
 ## Prerequisites
 
@@ -32,11 +32,11 @@
 
 ## Transition Workflow
 
 1. [Set up the transition tools](#workflow-setup)
 2. [Create an Rscript for your lesson](#Rscript)
 3. [Run the transition tool](#transition)
 4. [Set up your GitHub repository to receive the transitioned lesson](#github)
 5. [Post-transition steps](#post-transition)
 
 ::: callout
 Note: these steps assume your lesson exists in The Carpentries Incubator i.e. under the `carpentries-incubator` organisation on GitHub. If it does not, you will need to replace all of the folder names etc below accordingly.
@@ -84,11 +84,18 @@
 
 It is sufficient to create an empty file, named appropriately. This is available in the add-lesson.sh file, which will also provide hints about how the data can be transformed. 
 
+::::::::::::::::::::::::::::::::::::::: caution
+
+It is essential that you do not include a trailing `/` after YOUR-LESSON-NAME below.)
+
+:::::::::::::::::::::::::::::::::::::::::::::::
+
+
 ```bash
 bash add-lesson.sh carpentries-incubator/YOUR-LESSON-NAME
 ```
 
 But you may wish to populate this script with some function calls to clean up various common artifacts produced by the transition, or to preserve any [custom workflows](#custom-workflows) you have added to your lesson repository. Look at the `.R` scripts in the [`carpentries-incubator/`](https://github.com/carpentries/lesson-transition/tree/main/carpentries-incubator), [`datacarpentry`](https://github.com/carpentries/lesson-transition/tree/main/datacarpentry), [`librarycarpentry`](https://github.com/carpentries/lesson-transition/tree/main/librarycarpentry), and [`swcarpentry`](https://github.com/carpentries/lesson-transition/tree/main/swcarpentry) directories of the `lesson-transition` repository for inspiration.
 
 ### 3. Run the transition tool{#transition}
 
@@ -150,7 +157,7 @@
 To check how things are looking, [install the Workbench tools for your system](index.html#installation), then open R in this directory and run `sandpaper::serve()`.
 
 #### Optional: update your lesson's R script to produce a smoother transition
 While previewing this transitioned lesson site, you might see some problems in the content of your lesson site that appeared during the migration. Liquid comments (delineated by `{% comment %}` and `{% endcomment %}` tags) are one commonly-encountered artifact. Another is broken links to the lesson setup instructions, which are found at `index.html#setup` in a Workbench site. These can be fixed by editing the lesson after transition, but for a cleaner commit history on your lesson you might wish to delete the transitioned lesson directory (inside the `release` folder), modify the R script for your lesson to handle those issues, and re-run the transition tool. (See [_Create an Rscript for your lesson_](#Rscript) above.)
 
 #### If something goes wrong
 To go back to the start and try again, delete the directory for your lesson within the `release/` directory, i.e. `rm -rf release/carpentries-incubator/YOUR-LESSON-NAME`.