More descriptive summary (#2124)

* More descriptive summary

Slightly more descriptive summary of the purpose of this project.

* Clarify language.

Make it clear that this is for practice exercises and that test data is in JSON.

Co-authored-by: Katrina Owen <[email protected]>

Co-authored-by: Katrina Owen <[email protected]>

Author: gitonthescene

README.md

@@ -1,6 +1,10 @@
 # Problem Specifications
 
-Shared metadata for Exercism exercises.
+Repository for practice exercises to be used across tracks.
+This includes both problem statements available as markdown and test data as JSON described below.
+Note that tracks are not _required_ to use these exercises and some may be more or less appropriate to the given language.
+
+See the [new track roadmap](https://exercism.org/docs/building/tracks/new) for full details on setting up a new track.
 
 ## Reviewing Guidelines