Clarify hash lock description to emphasize preimage-hash matching

[g0tcha]

This commit updates the description of "Hash Locks" to improve technical accuracy and clarity. The previous phrasing:

"Requires revealing a preimage that hashes to a specific value"

has been replaced with:

"Requires revealing a preimage that matches a specific hash value"

[jrakibi]

Thanks @g0tcha this wording is much clearer