Finalize Update on PIConGPU Software Spotlight

@jandt-desy @konrad @jucke Added some final updates to MR !338 (merged) .

• Review here
• Edit here
• Summary of changes

_spotlights/picongpu.md

@@ -8,9 +8,10 @@ excerpt: PIConGPU is a relativistic Particle-in-Cell code running on graphic pro
 
 # Title for individual page
 title_image:
-title: PIConGPU - A Many-GPGPU Particle-in-Cell Code
+title: PIConGPU - A Heteregeneous Particle-in-Cell Code
 keywords:
     - GPU
+    - CPU
     - Particle-in-Cell
     - Simulation
 hgf_research_field: Matter