Adjust Benchmark Definitions for Operator

Depends on !131 (merged), !139 (merged), !153 (merged)

This is just an early draft, for a final version, we need to address the following items:

• Replace installation via install-configmaps.sh script by according additions to the Helm chart
• Reduce the amount of configMaps --> abandoned (see #240 (closed))
• Allow for additional benchmark definitions

docs/creating-a-benchmark.md

+
+# Defining a Benchmark
+
+Please note that to simply run a benchmark, it is not required to define one. Theodolite comes with a set of benchmarks, which are ready to be executed. See the Benchmarks and Executions docs page to learn more about our distinction between benchmarks and executions.
+
+
 * Create a benchmark for operator mode
 * Create a benchmark for standalone mode
 * Deploy a benchmark
@@ -12,6 +18,8 @@
 
 
 
+
+
 ## Creating a benchmark for standalone mode
 
 Creating a benchmark in standalone mode is similar to operator mode. However,