Please add guide about idField to doc

[ngocdaothanh]

The current doc: https://github.com/FirebaseExtended/reactfire/blob/main/docs/quickstart.md https://github.com/FirebaseExtended/reactfire/blob/main/docs/use.md

doesn't mention how to use idField and about NO_ID_FIELD.

I'm a new user of Firestore, and I even thought NO_ID_FIELD was set by Firestore server side service.

I luckily figured it out when reading the source code.

So please add guide about idField to doc, for the sake of other future users.

PS:

Please do not remove NO_ID_FIELD, as mentioned at "Remove NO_ID_FIELD key from data hooks": https://github.com/FirebaseExtended/reactfire/issues/295

Removing it even makes the usage of Firestore worse.

[matteocarpi]

I am also having a hard time understanding how this works.

@ngocdaothanh since there has been no edit of the docs do you have any useful lead to understand how this functions?

I am having a hard time understanding why it gets automatically added to docs that I write on the db, wether it is normal or it's an error and if it's an error how to avoid it.