[master] 943bbfa grammar micro-fix

[Nils Goroll]

commit 943bbfa21d63f5913023cd6fed87cd7412054ad2
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Tue Mar 27 11:12:26 2018 +0200

    grammar micro-fix

diff --git a/bin/varnishhist/varnishhist_options.h b/bin/varnishhist/varnishhist_options.h
index 0c04278..1bf1de7 100644
--- a/bin/varnishhist/varnishhist_options.h
+++ b/bin/varnishhist/varnishhist_options.h
@@ -54,7 +54,7 @@
 	    " tag we'll look for, a prefix to look for (can be empty,"	\
 	    " but must be terminated by a colon) and the field number"	\
 	    " of the value we are interested in. min and max are the"	\
-	    " boundaries of the graph in power of ten and default to"	\
+	    " boundaries of the graph in powers of ten and default to"	\
 	    " -6 and 3."						\
 	)