Interactive Dialog Docs: Remove mention of nonexistent limit of dialog elements

[mickmister]

Regarding Interactive Dialogs, the docs say that we can only use up to 5 elements in a dialog, but clearly the demo plugin way more. I can't see any limit being imposed in the code as well.

The task here is to update the documentation for this page to remove the mention of the limit of elements https://developers.mattermost.com/integrate/plugins/interactive-dialogs

_Issue created from a Mattermost message by @harshilsharma63._

[vishal-rathod-07]

@mickmister I would like to work on this can you assign this to me.

[mickmister]

Thank you @vishal-rathod-07!