How to grant a role permission to edit terms in a specific vocabulary
The only module I can think of is the Taxonomy access fix module, which has only a version for Drupal 7.


  This module
  
  
  adds 1 permission per vocabulary: "add terms in X"
  changes the way vocabulary specific permissions are handled
  changes the Taxonomy admin pages' access checks
  alters the vocabularies overview table to show only what you have access to edit or delete
  
  
  The module does what native Taxonomy lacks: more specific Taxonomy permissions (and checking them correctly).