Small update to documentation.

Author: arobenko

doc/WiresharkProtocolAnalysis.md

@@ -18,7 +18,7 @@ $> wireshark -X lua_script:/path/to/my_prot_plug.lua ...
 ```
 When using `tshark` instead of `wireshark` make sure to pass protocol name using `-O` command line option:
 ```
-$> wireshark -X lua_script:/path/to/my_prot_plug.lua -O "my_prot" ...
+$> tshark -X lua_script:/path/to/my_prot_plug.lua -O "my_prot" ...
 ```
 The protocol name is the first parameter in the `Proto(...)` invocation at the beginning of the generated `<schema>.lua` file.
 ```lua