Projects that rely on BOSL exceptions should say that they do

[daira]

This is important licensing information since it affects how those projects can be forked. zcash_script depends on orchard via zcash_primitives and zcash_note_encryption: see

zcash_script/Cargo.toml

Lines 57 to 58 in c9fbc44

	zcash_note_encryption = "0.1"
	zcash_primitives = { version = "0.6", features = ["transparent-inputs"] }

and zcash/librustzcash#576.

Suggested wording is:

Downstream code forks should note that the code in this repository depends on
the 'orchard' crate, which is licensed under the Bootstrap Open Source License.
A license exception is provided allowing some derived works that are linked or
combined with the 'orchard' crate to be copied or distributed under the original
licenses (in this case MIT / Apache 2.0), provided that the included portions of
the 'orchard' code remain subject to BOSL.
See https://github.com/zcash/orchard/blob/main/COPYING for details of which
derived works can make use of this exception.

See also:

• https://forum.zcashcommunity.com/t/bosl-or-mit-orchard/41439/118
• Projects that rely on BOSL exceptions should say that they do zcash/zcash#5931 (similar issue for zcashd)
• Projects that rely on BOSL exceptions should say that they do zcash/librustzcash#577 (PR for librustzcash)

[oxarbitrage]

I'm proposing the following actions and would like your input on whether we should implement them now. My plan is to submit a PR with the following changes:

1. Incorporate dual license files (APACHE/MIT) into this project, aligning with what Zebra and Zcash do.

2. Update the README by adding a license section, using a wording similar to Zebra's README as a reference: Zebra License Section.

3. Integrate the recommended wording from @daira regarding the BOSL into the newly created license section on the README.

Your thoughts on this would be greatly appreciated!