Add test-one usage to CLAUDE.md (#110)

Documents the test-one Makefile target for running individual
tests by name.

Author: SeanTAllen

CLAUDE.md

@@ -7,6 +7,7 @@ A Pony library for interacting with the GitHub REST API. Provides typed models,
 ```
 make ssl=3.0.x              # build + run unit tests + build examples
 make unit-tests ssl=3.0.x   # unit tests only
+make test-one t=TestName ssl=3.0.x  # run a single test by name
 make examples ssl=3.0.x  # build examples only
 make clean                  # clean build artifacts + corral deps
 make config=debug ssl=3.0.x # debug build