[docs] Have more details about FormControl, FormGroup etc.

[slavab89]

So i've been trying to understand what are the different From* components are used for and what are the differences between them and what i should use with what.
I was forced to go to the source to actually understand what they do.

Should we have a more detailed information about those components? The documentation on the API doc is pretty minimal
Currently they are used in several examples yet i didnt fully understand their purpose.

For example, in the checkbox example all the checkboxes are placed in a FormGroup. They can be placed in a FormControl as well with a FormLabel (am i correct?), yet if i put a disabled prop on FormControl, the checkboxes are not disabled. Not sure if that's intended or not

<FormControl disabled>
  <FormLabel component="legend">Header</FormLabel>
  <FormControlLabel control={<Checkbox value="A"} label="A" />} />
</FormControl>

[oliviertassinari]

I have added more information to the API pages. It's better but not perfect.

[Gems]

I believe the example mentioned above would be useful to have on the FormControl documentation page.

[oliviertassinari]

@Gems Do you want to add such an example for the composition of the form input elements?

[Gems]

@oliviertassinari at the moment I don’t feel confident in my full understanding of the design and what the example should be. I’ll take a deeper dive into the subject and may be could do something about it.

…

On Thu, 16 May 2019 at 15:31, Olivier Tassinari ***@***.***> wrote: @Gems <https://github.com/Gems> Do you want to add such an example for the composition of the form input elements? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#8159>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACHTCY7JADF7NPDDYMYKRTPVVO2HANCNFSM4D2RHSMA> .