Fix historical oversight regarding GRUB Argon2id

Patrick Steinhardt did the original work, importing PHC Argon2id
into GRUB; this fact was unintentionally excluded from the
Libreboot documentation.

Ax333l imported it into GRUB on the AUR, and Nicholas Johnson later
rebased it for GRUB 2.12, for use by the Libreboot project.

Credit where credit is due. The principle of the matter is that
I apologise for this oversight. It has now been corrected.

Signed-off-by: Leah Rowe <leah@libreboot.org>

site/docs/linux/grub_hardening.md

@@ -15,7 +15,10 @@ Full disk encryption
 ====================
 
 [Encrypted /boot with LUKS2 on argon2 key derivation is now
-possible](../../news/argon2.md).
+possible](../../news/argon2.md) - the work is based on that done by
+Patrick Steinhardt, importing PHC's Argon2 implementation. This was later added
+to GRUB 2.06 on the Arch Linux AUR by Ax333l, and Nicholas Johnson later rebased
+it for GRUB 2.12 to use in Libreboot's GRUB payload.
 
 This is covered in
 the [main Linux guide](./#encrypted-boot-via-luks2-with-argon2), in the

site/news/argon2.md

@@ -25,6 +25,9 @@ had been done, and I then merged Nicholas's work into Libreboot. Thank you,
 Nicholas! Thanks also go to [Axel](https://axelen.xyz/) who is the author of
 the original work that Nicholas imported from Archlinux AUR.
 
+The work on AUR, and Nicholas's update based on it, was ultimately based on
+the work done by Patrick Steinhardt for the GRUB project, importing PHC Argon2.
+
 Why does this matter?
 ---------------------
 

site/news/argon2.uk.md

@@ -25,6 +25,9 @@ AUR](https://aur.archlinux.org/cgit/aur.git/tree/?h=grub-improved-luks2-git&id=1
 Ніколас! Подяка також іде до [Аксель](https://axelen.xyz/), хто є автором
 оригінальної роботи, яку Ніколас імпортував з Archlinux AUR.
 
+The work on AUR, and Nicholas's update based on it, was ultimately based on
+the work done by Patrick Steinhardt for the GRUB project, importing PHC Argon2.
+
 Чому це має значення?
 ---------------------