Add Singleton Mode

[hhff]

• There should be a checkbox you can add that only allows the content editor to modify a single entry (ie - you set the schema, but there can only be one)

[dsbrianwebster]

Seriously! HOW is this not a thing??

[hhff]

Coming in hot @dsbrianwebster I love it!

Wanna make a PR??

[dsbrianwebster]

LOL 🌶️ , I didn't even notice this repo isn't part of Contentful. My B! I was searching around for how to create a single use content model in Contentful like in Dato, Prismic, and many other headless CMS products. It seems like Contentful has pretty much dug their heels in on that being an anti-pattern from their POW. But for things like site settings and what not it is very handy. Wish they would reconsider. Anyhow, this is the wrong place for that feedback 🤣