Update energy.md

docs.it4i/general/energy.md

@@ -23,7 +23,7 @@ The [arithmetic intensity][2] is a measure of floating-point operations (FLOPs)
 
 In general, the processor frequency [capping][3] has low performance impact for memory bound computations (arithmetic intensity below the [ridge point][2]). For processor bound computations (arithmetic intensity above the [ridge point][2]), the impact is proportional to the frequency reduction.
 
-On Karolina, runtime increase **up to 16%** is observed for arithmeticaly intensive CPU workloads and **up to 10%** for intensive GPU workloads. **No slowdown** is observed for memory bound workloads.
+On Karolina, runtime increase **up to 16%** is [observed][4] for arithmeticaly intensive CPU workloads and **up to 10%** for intensive GPU workloads. **No slowdown** is [observed][4] for memory bound workloads.
 
 ### Energy Efficiency
 
@@ -44,3 +44,4 @@ None implemented yet.
 [1]: https://en.wikipedia.org/wiki/Roofline_model
 [2]: https://dl.acm.org/doi/10.1145/1498765.1498785
 [3]: https://slovnik.seznam.cz/preklad/anglicky_cesky/capping
+[4]: Energy_saving_Karolina.pdf