docs: retitle usage.rst "Using the parser"

The page has roughly tripled — 414 lines across 13 sections — since it
was named. "Getting started" now sets the wrong expectation in both
directions: a newcomer expects something short, and a reader returning
to look up how to sort by surname or what ambiguities does never thinks
to check a page called Getting started.

"Using the parser" also aligns the title with the URL it has always had
(usage.html), and echoes v1's "Using the HumanName Parser" for readers
coming back. Dropping HumanName from it on purpose: 2.0's entry point is
parse(), and naming the compatibility layer in the title of the main
tour would point newcomers at the wrong API.

The README already showed the strain — it linked "Getting started" and
then glossed it as "the full tour". Gloss updated too; its list of
contents predated input shapes, attaching words, ambiguities and tokens.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: derek73

README.rst

@@ -36,7 +36,7 @@ for combining or splitting them further.
 Learn more
 ----------
 
-* `Getting started <https://nameparser.readthedocs.io/en/latest/usage.html>`__ — the full tour: parsing, aggregates, dicts, rendering, dedup
+* `Using the parser <https://nameparser.readthedocs.io/en/latest/usage.html>`__ — the full tour: input shapes, aggregates, rendering, comparison, ambiguities, tokens
 * `Customizing the parser <https://nameparser.readthedocs.io/en/latest/customize.html>`__ — vocabulary, behavior, and presentation
 * `Locale packs <https://nameparser.readthedocs.io/en/latest/locales.html>`__ — opt-in bundles for East Slavic patronymics, Turkic markers, and more
 * There's also a CLI: ``python -m nameparser --json "Doe, John"``

docs/release_log.rst

@@ -80,7 +80,7 @@ Release Log
 
     **Documentation**
 
-    - Rewrite the documentation new-API-first: a new front page and README, ``usage.rst`` as a 2.0 getting-started tour, a principle-first ``customize.rst``, a reference split into the 2.0 API and the compatibility layer, and new pages for :doc:`concepts`, :doc:`locales` and :doc:`migrate` -- the last carrying full attribute and configuration maps from v1 names to 2.0 names (#262). The 1.x documentation remains online as the readthedocs ``stable`` build
+    - Rewrite the documentation new-API-first: a new front page and README, ``usage.rst`` as a tour of the 2.0 API, a principle-first ``customize.rst``, a reference split into the 2.0 API and the compatibility layer, and new pages for :doc:`concepts`, :doc:`locales` and :doc:`migrate` -- the last carrying full attribute and configuration maps from v1 names to 2.0 names (#262). The 1.x documentation remains online as the readthedocs ``stable`` build
 
     Parsing changes were checked against a 486-name differential corpus
     built from the v1 test banks; everything not listed above parses

docs/usage.rst

@@ -1,5 +1,5 @@
-Getting started
-===============
+Using the parser
+================
 
 Requires Python 3.11+.  ``pip install nameparser``