Update Data Dictionary.txt

[Ennego]

Specified max pixels for images are 4096 pixels on a side

[nga-automation]

Hi @Ennego — thanks for this. This PR now conflicts with main: #30 updated documentation/Data Dictionary.txt to remove the media_items and media_relationships sections (those media tables are no longer part of the open data program). Your branch predates that change, so it no longer applies cleanly.

Could you please rebase onto the current main and resubmit your edits on top of the updated Data Dictionary (making sure not to re-add the removed media sections)? Happy to review once it's refreshed. Thanks!