docs: polish README prose per documentation rules

[indykish]

What

README prose polish, driven by two DOCUMENTATION_RULES.md language rules:

• DOC-02 (≤25 words/sentence) — split the intro's 35-word sentence into four sentences, each under the limit. Kept the "posts evidenced answers, never chats" punchline intact.
• DOC-04 (active voice) — flipped the Publishing line from passive ("Changes pushed… are deployed automatically via…") to active ("The Mintlify GitHub app deploys every change…").

Scope

README only. No code, no published docs.json pages, no behavior change.

Verification

• gitleaks clean.
• Pre-commit hooks green (22 tests + documentation check passed).

Not changed (deliberate)

• Tagline, ~/Projects/dotfiles/… contributor pointer, command/output blocks, and the trailing preview-URL line — none are DOC-rule hits.

Greptile Summary

This PR polishes the README prose to follow the documentation rules.

• Splits the introduction into shorter sentences.
• Rewrites the publishing guidance in active voice.
• Preserves the existing meaning and links.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed text.
• The product workflow, approval semantics, deployment claim, and links remain unchanged.

Important Files Changed

Filename	Overview
README.md	Improves sentence length and voice without changing documented behavior or links.

_{Reviews (1): Last reviewed commit: "docs: polish README prose per documentat..." | Re-trigger Greptile}