Mention Bytes is case insensitive

[sebastiantf]

Bytes being case insensitive is a really helpful info for subgraph clients. Couldn't find a mention of this in the docs, and had to gather from Discord

Would be helpful to have a mention of this in the docs, maybe here: https://thegraph.com/docs/en/developing/creating-a-subgraph/#optional-and-required-fields

Although that section looks misplaced. Might be more appropriate to have that as a separate section with a separate heading