docs: add Coming-from-Python section + fix stale counts

[conorbronsdon]

Summary

Two documentation changes:

1. Coming from Python — a short side-by-side section (near the top, after
   the intro) mapping the familiar Python API to this library's real API.
   Every snippet was extracted from this repo's own examples/ and test/;
   nothing was invented.
2. Accuracy fixes — Suite copy Ten -> Eleven and added mojo-xml link. Corrected protocol-test count 29 -> 34 in README (x2) and CHANGELOG. Re-verified by counting: 34 protocol tests in test/test_resp.mojo + 21 integration tests in test/test_integration.mojo.

Test counts were re-verified by actually counting the test functions in the
repo (not trusting the prior text).

From an automated review (personal-context#62); drafted by Claude Code — please review the Coming-from-Python snippets for API accuracy.

[conorbronsdon]

🤖 Independent Claude review: Ready.

Verified every Mojo snippet in the diff against real source — no invented APIs.

"Coming from Python" table — all methods exist in src/redis/client.mojo and are exercised in examples/demo.mojo:

• Redis(host, port) → Redis.__init__(out self, var host, port) ✓
• set("k","v") / set("k","v", ex=60) → set(..., ex: Optional[Int] = None) ✓ (demo L26/L29)
• get("k").value() → get(...) -> Optional[String] ✓ (demo L27)
• incr / decr → both present ✓
• hset("h","f","v") / hgetall("h") → hset(key, field, value), hgetall(key) -> Dict ✓ (demo L45-47)
• Optional note (.value() / Bool(...)) matches the real Optional[String] return type ✓

Counts:

• "34 protocol unit tests" (CHANGELOG + README ×2) → exactly 34 test_ fns in test/test_resp.mojo ✓
• "Eleven pure-Mojo libraries" → 10 sibling libs listed + mojo-redis itself = 11, internally consistent ✓ (mojo-xml correctly added)

Python-side snippets are idiomatic redis-py (redis.Redis(host, port), set(..., ex=), hset(h, f, v)).

No blocking issues.

[conorbronsdon]

Docs review (sonnet): SHIP

redis-py-shaped table (Redis(host, port), set/get/incr/hset/hgetall, ex=) matches src/redis/client.mojo exactly; the .value() caveat for get's Optional[String] is accurate and consistent with the existing README example. The 29→34 protocol-test-count fix is a genuine correction (recounted 34 in test/test_resp.mojo), applied consistently across README ×2 + CHANGELOG with no stale "29" left. Ship.