Update README for clarity and accuracy #55

Job	Run time
pytester (macos-latest, 3.11, lightning, latest)	52s
pytester (windows-latest, 3.11, lightning, latest)	1m 18s
pytester (ubuntu-latest, 3.10, lightning, latest)	1m 11s
pytester (macos-latest, 3.10, lightning, latest)	43s
pytester (ubuntu-latest, 3.10, lightning, oldest)	1m 12s
pytester (ubuntu-latest, 3.12, lightning, latest)	1m 18s
pytester (macos-latest, 3.12, lightning, latest)	52s
pytester (ubuntu-latest, 3.13, lightning, latest)	1m 6s
pytester (windows-latest, 3.12, lightning, latest)	1m 18s
pytester (ubuntu-latest, 3.11, lightning, latest)	1m 13s
pytester (windows-latest, 3.13, lightning, latest)	1m 12s
pytester (macos-latest, 3.13, lightning, latest)	45s
pytester (windows-latest, 3.10, lightning, latest)	1m 28s
guardian-unittest	2s
	14m 30s

Provide feedback