[1.19] Small progression guide mistake

[Darkxell]

Hi, just opening a git issue to notify a small documentation mistake from the 1.19 docs. Blazes spawn in nether forteresses, not strongholds:

1.19 progression.md "Obtain Blaze Powder by killing Blazes that spawn in Strongholds"

Thanks for the mod!

[jsorrell]

Thanks for pointing this out