locale: better explenation for team membership and granted access (#4417)

As discussed here https://crowdin.com/translate/gogs/1/enus-cs#378 I'm suggesting this update.

conf/locale/locale_en-US.ini

@@ -962,9 +962,9 @@ teams.add_team_member = Add Team Member
 teams.delete_team_title = Team Deletion
 teams.delete_team_desc = As this team will be deleted, members of this team may lose access to some repositories. Do you want to continue?
 teams.delete_team_success = Given team has been deleted successfully.
-teams.read_permission_desc = This team grants <strong>Read</strong> access: members can view and clone the team's repositories.
-teams.write_permission_desc = This team grants <strong>Write</strong> access: members can read from and push to the team's repositories.
-teams.admin_permission_desc = This team grants <strong>Admin</strong> access: members can read from, push to, and add collaborators to the team's repositories.
+teams.read_permission_desc = Membership in this team grants <strong>Read</strong> access: members can view and clone the team's repositories.
+teams.write_permission_desc = Membership in this team grants <strong>Write</strong> access: members can read from and push to the team's repositories.
+teams.admin_permission_desc = Membership in this team grants <strong>Admin</strong> access: members can read from, push to, and add collaborators to the team's repositories.
 teams.repositories = Team Repositories
 teams.search_repo_placeholder = Search repository...
 teams.add_team_repository = Add Team Repository