Document breaking change within v0.10.x family

[tlake]

What does this pull request do? Introduces a warning on the 'releases' page that documents issue #572

How should this be tested? Make sure it looks good and is adequately detailed.

Checklist

• ~[ ] Unit tests~
• ~[ ] Smoke tests (if applicable)~
• ~[ ] System tests (if applicable)~
• [x] Documentation (if applicable)

closes #572

[nehayward]

Looks good.