Add prerequisites to Practice Exercises (#330)

* Two-fer

* Armstrong numbers

* add prerequisites

* fill in concepts array

* add `practices` entries

* update uuids

* remove trailing comma

* remove duplicate

* add prerequisites key

* replace key features

* remove `basics`

Co-authored-by: Erik Schierboom <[email protected]>

* remove concepts without docs

Co-authored-by: Erik Schierboom <[email protected]>

Author: bobbicodes

.gitignore

@@ -20,3 +20,4 @@ pom.xml.asc
 *.nrepl-port
 .clj-kondo
 .lsp
+*.calva