Fixed docu

Author: DiegoKrupitza

docs/user_guide.md

@@ -232,8 +232,8 @@ BM_base_ten_args/1k             2.27 ns         2.26 ns      5845511
 BM_base_ten_args/10k            2.27 ns         2.26 ns      6252791
 BM_base_ten_args/32k            2.27 ns         2.26 ns      6208426
 BM_base_ten_args/100k           2.27 ns         2.26 ns      6129597
-BM_base_ten_args/1m             2.28 ns         2.28 ns      5988024
-BM_base_ten_args/1bn            2.25 ns         2.25 ns      6211180
+BM_base_ten_args/1M             2.28 ns         2.28 ns      5988024
+BM_base_ten_args/1B             2.25 ns         2.25 ns      6211180
 ```
 
 ## Disabling Benchmarks