Corrected a character in usage output and updated README.rst

Author: henry.potgieter

README.rst

@@ -144,8 +144,8 @@ The full usage::
           Use tmux colors in output
   -p, --powerline-left
 	  Use powerline left symbols throughout the output, enables --colors
-  -n, --nerd-graph
-	  Use NerdFont characters to render CPU graph as vertical bar chart
+  -v, --vertical-graph
+	  Use vertical bar chart for CPU graph
   -q, --powerline-right
 	  Use powerline right symbols throughout the output, enables --colors
   -i <value>, --interval <value>

common/main.cc

@@ -129,7 +129,7 @@ void print_help()
     << "\tUse powerline left symbols throughout the output, enables --colors\n"
     << "-q, --powerline-right\n"
     << "\tUse powerline right symbols throughout the output, enables --colors\n"
-    << "-n, --vertical-graph\n"
+    << "-v, --vertical-graph\n"
     << "\tUse vertical bar chart for CPU graph\n"
     << "-i <value>, --interval <value>\n"
     << "\tSet tmux status refresh interval in seconds. Default: 1 second\n"