add readme to lit-sdk in anticipation of publishing

[glitch003]

No description provided.

[Copilot]

Pull request overview

This pull request adds a README file to the lit-sdk package in preparation for publishing it. The README provides essential documentation for users, clarifying that this is a low-level SDK and directing them to more user-friendly alternatives.

Key Changes:

• Added a new README.md for the lit-sdk package describing its purpose and guiding users to higher-level alternatives
• Updated the git commit hash in git_info.rs (standard automated update)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
rust/lit-node/lit-sdk/README.md	New README documenting the low-level SDK and referring users to the Lit Rust SDK and Lit JS SDK for easier usage
rust/lit-node/lit-node/src/git_info.rs	Updated git commit hash constant (automated change)

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[github-actions]

PASS [ 43.162s] (3/3) lit_node::test toxiproxy::perf_tests::load_with_no_latency
PASS [ 43.392s] (2/3) lit_node::test toxiproxy::perf_tests::load_with_50ms_latency_single_link
PASS [ 91.073s] (1/3) lit_node::test toxiproxy::perf_tests::load_with_50ms_latency_all_links