Missing documentation on data-ampdevmode

[Gregable]

📖 Missing or Out-of-Date Documentation

Problem

We should document somewhere the behavior of data-ampdevmode.

Location

I don't have a strong opinion. Mostly this would be critical for search requests.

Content type

Reference probably.

Information architecture (optional)

Here's where the attribute was introduced:
ampproject/amphtml#20974

It was originally used only as an internal thing for the Wordpress plugin, but it appears that interest is growing. Weston wrote some additional docs here.

There is a concise summary in this comment. The "first meaning" is what should be documented for now as the "second meaning" part is still under development.

I can also answer any questions if the behavior is unclear.

[matthiasrohmer]

After Ben's recent rewrite of the amp-script docs theres actually a tip at the end of the Calculating the script hash section but maybe we can have it somewhere more prominent...

/cc @morsssss

[morsssss]

Agreed! This attribute isn't documented at all. I made an issue for this a little while ago: #4215

Closing this as a duplicate.