Update john.md

Added nested list documentation.

github-clinic/john.md

@@ -42,3 +42,8 @@ We can include an image with the same `[]()` pattern, but note the preceding exc
 *Note that this image lives in the folder one level above our `github-clinic` folder, and we indicate that with the two periods `..`* 
 
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+#### Nests
+Nests are little pockets of home
+*  twigs and feathers and flakes of shell
+   *  but also something else entyre
+      *  list within lists, oh, can this end well?