bug#44196: [PATCH 2/3] system: Add store-directory-prefix to boot-parameters.

[Miguel Ángel Arruga Vivas]

I've pushed this last patch as 582cf9257cd1f9c969fbba5eb1c336ac8b975cde
with the following additions:
 - A pointer to this issue in the commit message.
 - A description of store-directory-prefix on the commit message.
 - A better version (I hope) of the comment inside <boot-parameters>.

Thank you very much!
Miguel