docs: use parse API in the README example

[MbappeWU]

The README constructs IniConfig() but shows values with inline comments removed. The constructor deliberately preserves those comments for compatibility, so the first displayed result is currently incorrect.

Use the IniConfig.parse() API introduced in #70, and explain how the constructor and strip_inline_comments=False preserve comments. This updates the documented example without changing parser behavior.

Validation on Python 3.13.12 with the original frozen development dependencies:

• Unchanged README doctest: one failure (value1 expected; value1 # comment returned).
• Updated README doctest: passed; original parser suite: 51 passed before and after.
• Actual Setuptools wheel/sdist build and strict Twine checks: passed. The updated README matches the wheel long description and sdist README; all four tracked runtime files and py.typed content match source.
• A fresh neutral wheel installation passed three public API assertions for default parsing, constructor compatibility, and explicit comment preservation.
• git diff --check: passed.

The generated version module has the same version as package metadata; its commit ID is absent in the wheel built from the sdist, as expected without Git metadata. These are local validation distributions, not a release.

AI assistance: prepared with OpenAI Codex and checked by a separate AI review. No human review is claimed by those checks.