docs(httpserver): correct tier from 4 to 3

httpserver depends on launcher (Tier 2), placing it at Tier 3.
With launcher corrected from Tier 5 to Tier 2, httpserver's tier
drops accordingly.

compliance_test.go

@@ -0,0 +1,19 @@
+package httpserver_test
+
+import (
+	"code.nochebuena.dev/go/httpserver"
+	"code.nochebuena.dev/go/launcher"
+	"github.com/go-chi/chi/v5"
+)
+
+type testLogger struct{}
+
+func (t *testLogger) Info(msg string, args ...any)              {}
+func (t *testLogger) Error(msg string, err error, args ...any) {}
+
+// Compile-time checks.
+var _ httpserver.Logger = (*testLogger)(nil)
+
+// HttpServerComponent must satisfy both launcher.Component and chi.Router.
+var _ launcher.Component = httpserver.New((*testLogger)(nil), httpserver.Config{})
+var _ chi.Router         = httpserver.New((*testLogger)(nil), httpserver.Config{})