Add Pulseahead to showcase (#3826)

Author: incognitosj

docs/src/assets/showcase/pulseahead.com.png

@@ -227,4 +227,5 @@ import FluidGrid from './fluid-grid.astro';
 		href="https://astro-snapshot.johng.io"
 		thumbnail="astro-snapshot.johng.io.png"
 	/>
+	<Card title="Pulseahead Docs" href="https://www.pulseahead.com/docs" thumbnail="pulseahead.com.png" />
 </FluidGrid>