[Whitepapers] Format Sha256 and SHA-256 consistently

[reveloper]

Check and fix the formatting of SHA-256 / Sha256 words in the whitepaper documents according to the following rules:

• If the word Sha256 refers to a general mention of the algorithm in the text, it should be written as SHA-256 text.

Example needs to be fixed:

• If the word Sha256 appears in a formula or refers to an internal formula in the Whitepaper, render it as the math variable Sha256 (should not be SHA256 or sha256).

Example needs to be fixed:

[fakela]

Just so I am clear on this @reveloper

If the word Sha256 is regular in the text then it should be SHA-256

And if in a formula Should be Sha256 rendered as a math variable