Merge branch 'patch-1' into 'master'

Update volunteer.yml with more precise feature description.

See merge request !97

books/volunteer.yml

 name: CiviVolunteer
-description: Provides tools for signing up, managing, and tracking volunteers
+description: Create Volunteer Projects, manage schedules, sign-up volunteers, and log volunteer hours.
 langs:
   en:
     repo: 'https://github.com/civicrm/org.civicrm.volunteer'
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