add missing description for solana-lattice-hash

[yihau]

Problem

need the description for publishing crate

Summary of Changes

add a basic one

[mergify]

Backports to the beta branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule. Exceptions include CI/metrics changes, CLI improvements and documentation updates on a case by case basis.

[brooksprumo]

Why do we need to publish this crate?

[yihau]

we don't assign publish = false in #2204 so I assume we wanna publish it 🤔
even if we don’t publish the crate, we will face another issue because we publish solana-accounts-db, and this crate is one of its dependencies. iirc, we usually publish deps as well