update readme benchmark

Author: matiii

README.md

@@ -23,6 +23,32 @@ var dijkstra = new Dijkstra<int, string>(graph);
 DijkstraResult result = dijkstra.Process(0, 1); //result contains the shortest path
 result.GetPath();
 ```
+## Benchmark
+
+For Graph where number of vertices is 1 000 000 and number of edges is 10 000 000. Benchmark is available on the [benchmark](https://github.com/matiii/Dijkstra.NET/blob/benchmark/src/Dijkstra.NET/Dijkstra.NET.Benchmark/DijkstraBenchmark.cs) branch.
+
+```c#
+
+```
+
+```ini
+
+Host Process Environment Information:
+BenchmarkDotNet.Core=v0.9.9.0
+OS=Microsoft Windows NT 6.2.9200.0
+Processor=Intel(R) Core(TM) i7-6820HQ CPU 2.70GHz, ProcessorCount=8
+Frequency=2648439 ticks, Resolution=377.5809 ns, Timer=TSC
+CLR=MS.NET 4.0.30319.42000, Arch=64-bit RELEASE [RyuJIT]
+GC=Concurrent Workstation
+JitModules=clrjit-v4.6.1586.0
+
+Type=DijkstraBenchmark  Mode=SingleRun  LaunchCount=1  
+WarmupCount=1  TargetCount=1  
+
+```
+  Method |      Median |    StdDev |
+-------- |------------ |---------- |
+ GetPath | [695.5040 us](https://www.google.pl/#q=695+us+to+sec) | 0.0000 us |
 
 ## License