Change "running" to "started" in progress monitoring

[wlandau]

Prework

• Read and agree to the code of conduct and contributing guidelines.
• If there is already a relevant issue, whether open or closed, comment on the existing thread instead of posting a new issue.
• For any problems you identify, post a minimal reproducible example like this one so the maintainer can troubleshoot. A reproducible example is:
  • Runnable: post enough R code and data so any onlooker can create the error on their own computer.
  • Minimal: reduce runtime wherever possible and remove complicated details that are irrelevant to the issue at hand.
  • Readable: format your code according to the tidyverse style guide.

Description

The term "running" is misleading because targets does not use any kind of heartbeat or connection to verify job status. It only records whether a target began and whether it completed. "Started" is more accurate.