docs: add Graviton 4 to hash benchmarks

benches/README.md

@@ -21,6 +21,7 @@ The second scenario is that of sequential hashing where we take a sequence of le
 | Apple M1 Pro        | 76 ns  | 245 ns  |  1.5 µs   |  9.1 µs   | 5.2 µs  | 2.7 µs  |
 | Apple M2 Max        | 71 ns  | 233 ns  |  1.3 µs   |  7.9 µs   | 4.6 µs  | 2.4 µs  |
 | Amazon Graviton 3   | 108 ns |         |           |           | 5.3 µs  | 3.1 µs  |
+| Amazon Graviton 4   | 96 ns  |         |           |           | 5.1 µs  | 2.8 µs  |
 | AMD Ryzen 9 5950X   | 64 ns  | 273 ns  |  1.2 µs   |  9.1 µs   | 5.5 µs  |         |
 | AMD EPYC 9R14       | 83 ns  |         |           |           | 4.3 µs  | 2.4 µs  |
 | Intel Core i5-8279U | 68 ns  | 536 ns  |  2.0 µs   |  13.6 µs  | 8.5 µs  | 4.4 µs  |
@@ -33,13 +34,14 @@ The second scenario is that of sequential hashing where we take a sequence of le
 | Apple M1 Pro        | 1.0 µs | 1.5 µs  |  19.4 µs  |   118 µs  | 69 µs   | 35 µs   |
 | Apple M2 Max        | 0.9 µs | 1.5 µs  |  17.4 µs  |   103 µs  | 60 µs   | 31 µs   |
 | Amazon Graviton 3   | 1.4 µs |         |           |           | 69 µs   | 41 µs   |
+| Amazon Graviton 4   | 1.2 µs |         |           |           | 67 µs   | 36 µs   |
 | AMD Ryzen 9 5950X   | 0.8 µs | 1.7 µs  |  15.7 µs  |   120 µs  | 72 µs   |         |
 | AMD EPYC 9R14       | 0.9 µs |         |           |           | 56 µs   | 32 µs   |
 | Intel Core i5-8279U | 0.9 µs |         |           |           | 107 µs  | 56 µs   |
 | Intel Xeon 8375C    | 0.8 µs |         |           |           | 110 µs  |         |
 
 Notes:
-- On Graviton 3, RPO256 and RPX256 are run with SVE acceleration enabled.
+- On Graviton 3 and 4, RPO256 and RPX256 are run with SVE acceleration enabled.
 - On AMD EPYC 9R14, RPO256 and RPX256 are run with AVX2 acceleration enabled.
 
 ### Instructions