Update user_guide.md (#1863)

PR for Issue #819: Fix Suffix in Console Format Table
This PR fixes an issue with an incorrect suffix displayed in the console output. 

Fixes #819.
diff --git a/docs/user_guide.md b/docs/user_guide.md
index 64566f1..046d7de 100644
--- a/docs/user_guide.md
+++ b/docs/user_guide.md
@@ -82,9 +82,9 @@
 ```
 Benchmark                               Time(ns)    CPU(ns) Iterations
 ----------------------------------------------------------------------
-BM_SetInsert/1024/1                        28928      29349      23853  133.097kB/s   33.2742k items/s
-BM_SetInsert/1024/8                        32065      32913      21375  949.487kB/s   237.372k items/s
-BM_SetInsert/1024/10                       33157      33648      21431  1.13369MB/s   290.225k items/s
+BM_SetInsert/1024/1                        28928      29349      23853  133.097kiB/s   33.2742k items/s
+BM_SetInsert/1024/8                        32065      32913      21375  949.487kiB/s   237.372k items/s
+BM_SetInsert/1024/10                       33157      33648      21431  1.13369MiB/s   290.225k items/s
 ```
 
 The JSON format outputs human readable json split into two top level attributes.