Update Planet Drupal guidelines to explicitly exclude advertising posts

Problem/Motivation

Paid advertising has begun to appear on Planet Drupal → .

Two recent examples that appeared in the aggregator:

• https://assoc.drupal.org/blog/drejer/sponsored-post-blink-reaction-prope...
• https://assoc.drupal.org/blog/felicianotech/sponsored-post-reclaim-contr...

The Planet Drupal guidelines → list spam as a basis for removal from the feed, but don't explicitly define what spam is.

The two listed posts are both from the Drupal Association. Presumably the DA is not exempt from the guidelines that apply to other Drupal Planet aggregation sources. If everyone used their feed as a way of disseminating paid advertising, the appropriateness and utility of the aggregator content would go downhill fast.

Proposed resolution

Update the Planet Guidelines to add the following under the "Content that doesn't fit Planet Drupal" heading:

Any post that consists primarily or exclusively of paid advertisement, sponsored content, or "advertorial" copy.

Remaining tasks

User interface changes

API changes