docs(smtp): fix fictional launcher.Register/health.Register in doc examples (#2)

The package-doc examples showed a fictional launcher.Register / health.Register
API (and launcher.Append as a package func). Corrected to the real wiring:
lc.Append + web/health.NewHandler(...).ServeHTTP.

Documentation-only. No code, API, or dependency changes; version stays v1.1.0
(the v1.1.0 tag is moved to include this fix). Verified by compiling the
corrected pattern against the real API.

Reviewed-on: #2
Co-authored-by: Rene Nochebuena Guerrero <rene@nochebuena.dev>
Co-committed-by: Rene Nochebuena Guerrero <rene@nochebuena.dev>

README.md

@@ -19,8 +19,9 @@
 import "code.nochebuena.dev/einherjar/smtp"
 
 mailer := smtp.New(logger, smtp.DefaultConfig())
-launcher.Append(mailer)   // OnInit verifies credentials; OnStop is a no-op
-health.Register(mailer)   // dial check; LevelDegraded
+lc.Append(mailer)   // OnInit verifies credentials; OnStop is a no-op
+// mailer is observability.Checkable (dial check, LevelDegraded):
+srv.Get("/health", health.NewHandler(logger, mailer).ServeHTTP)
 ```
 
 When `cfg.Host` is empty, `New` returns a no-op that logs every `Send` call at debug level and always returns nil. No code changes are needed between environments.

doc.go

@@ -12,8 +12,12 @@
 // # Lifecycle Registration
 //
 //	client := smtp.New(logger, cfg)
-//	launcher.Register(client)
-//	health.Register(client)
+//	lc.Append(client) // lifecycle: OnInit → OnStop
+//
+// client satisfies [observability.Checkable], so it can back a health endpoint via
+// web/health.NewHandler:
+//
+//	srv.Get("/health", health.NewHandler(logger, client).ServeHTTP)
 //
 // # Sending
 //