Fix incorrect variable in invitation script.

Dependencies

• [2] UOG5H2TW Default work logging credit to logged-in user.
• [3] G4BS4NND Add simple shell script demonstrating how to invite a companion.

Change contents

• replacement in scripts/invite.sh at line 22
  [2.745]→[2.745:819](∅→∅)
  − --data '' \

  − "https://aftok.com/projects/$PROJECT/invite?email=$EMAIL"
  [2.745]
  + --data '{}' \

  + "https://aftok.com/projects/$PID/invite?email=$EMAIL"