chore(book): Add patch for sha2 0.9.9 (#1921)

Author: ratankaliani

book/docs/writing-programs/patched-crates.md

@@ -28,6 +28,7 @@ To use the patched libraries, you can use corresponding patch entries in your pr
 
 ```toml
 [patch.crates-io]
+sha2-v0-9-9 = { git = "https://github.com/sp1-patches/RustCrypto-hashes", package = "sha2", tag = "patch-sha2-0.9.9-sp1-4.0.0-rc.3" }
 sha2-v0-10-6 = { git = "https://github.com/sp1-patches/RustCrypto-hashes", package = "sha2", tag = "patch-sha2-0.10.6-sp1-4.0.0-rc.3" }
 sha2-v0-10-8 = { git = "https://github.com/sp1-patches/RustCrypto-hashes", package = "sha2", tag = "patch-sha2-0.10.8-sp1-4.0.0-rc.3" }
 sha3-v0-10-8 = { git = "https://github.com/sp1-patches/RustCrypto-hashes", package = "sha3", tag = "patch-sha3-0.10.8-sp1-4.0.0-rc.3" }