Updated roadmap in concepts.md

Author: kushalbakshi

docs/src/concepts.md

@@ -31,7 +31,7 @@ One notable consession was made in development: acronyms in DataJoint do not per
 
 ## Roadmap
 
-Further development of this Element is community driven. Upon user requests we will continue adding features to this Element, such as improved topological referencing.
+Further development of this Element is community driven. Upon user requests we will continue adding features to this Element, such as improved region- and subregion-based topological referencing.
 
 ## References