[docs] Mention the "direction=column" removal from the Grid in v9 migration guide

[sprietNathanael]

Related page

https://mui.com/material-ui/migration/upgrade-to-v9/#gridlegacy

Kind of issue

Unclear explanations

Issue description

There should be a strong warning for the Grid API incompatibility between mui@7 and mui@9

Context

I already did the migration a while ago of all my legacy grids from mui@5 to mui@6, so I did not check the "migration guide from legacy grids", thinking the migration was already done.
In Grid documentation for v7, the direction "column" was mentioned as "not supported", but in the API it was not marked as deprecated.
I was taken aback when upgrading from mui@7 to mui@9, seeing half of my grids failing.
(side note : I always thought of the Grid component as a flex container / item, so it was very natural for me to use the direction, like I would do with flex-direction. I wonder on the need to separate between Grid and Stack)

Search keywords: grid direction column

[sprietNathanael]

And in the same way, it is not mentioned explicitly that many props will not work anymore.
For example, I could do

<Grid
	container
	direction='column'
	rowGap={1}
	flexGrow={1}
	sx={{ width: '100%' }}
	alignItems='flex-start'
	justifyContent={props.step.content ? 'space-between' : 'flex-start'}
>

Where now I have to use sx.

<Grid
	container
	sx={{
		width: '100%',
		flexDirection: 'column',
		alignItems: 'flex-start',
		justifyContent: props.step.content ? 'space-between' : 'flex-start',
		rowGap: 1,
		flexGrow: 1,
	}}
>

I don't really understand what happened, but I find the migration guide is really missing this valuable information (or maybe I haven't read it correctly, and if that's the case, I'm very sorry for the disturbance)

EDIT
Ok sorry, my bad 😅, it's written explicitly in the migration guide...

[BabuBahir]

so @sprietNathanael this issue would be closed right ? :)

[ZeeshanTamboli]

First of all, I agree that the direction values column and column-reverse should have been marked as deprecated in v7. However, they have now been removed in v9 in #47564.

It looks like we forgot to mention this in the "Upgrade to v9" migration guide. It was, however, called out in the PR discussion: #47564 (comment).

Would you be interested in opening a PR to add this to the "Upgrade to v9" migration guide? I'd be happy to review it.

[kalayciburak]

I'll open a PR to document the Grid direction column / column-reverse removal in the Upgrade to v9 migration guide.

[Rajjoshi77]

Hi! I'd like to work on this documentation improvement. Could you assign it to me?