fixing typos in bbsim chart doc

Change-Id: I6f99a38ec0e3edf946473d43c42a68d5027d713d
diff --git a/charts/bbsim.md b/charts/bbsim.md
index cabc6c6..74b75fa 100644
--- a/charts/bbsim.md
+++ b/charts/bbsim.md
@@ -9,10 +9,10 @@
 
 ## Set a different number of ONUs
 
-You can configure the number of ONUs trough a parameter in the installation:
+You can configure the number of ONUs through a parameter in the installation:
 
 ```shell
-helm install -n bbsim bbsim --set onus_per_pon_port={number_od_onus}
+helm install -n bbsim bbsim --set onus_per_pon_port={number_of_onus}
 ```
 
 ## Set a different mode