[PATCH] docs: add note about experimental API in LTS

[Bruce Richardson]

On Fri, Oct 20, 2023 at 03:19:30PM +0100, Kevin Traynor wrote:
> The justification and impact for changing experimental API on LTS
> branches is different from the main branch. So the policy that is
> being used for allowing experimental APIs to change is stricter on
> the LTS branches.
> 
> This was not documented anywhere, so add some documentation.
> 
> Suggested-by: David Marchand <david.marchand at redhat.com>
> Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
> ---
Acked-by: Bruce Richardson <bruce.richardson at intel.com>