fix "propertes" typos in comments

less/popovers.less

@@ -11,7 +11,7 @@
   display: none;
   max-width: @popover-max-width;
   padding: 1px;
-  // Reset font and text propertes given new insertion method
+  // Reset font and text properties given new insertion method
   font-family: @font-family-base;
   font-size: @font-size-base;
   font-weight: normal;

less/tooltip.less

@@ -9,7 +9,7 @@
   z-index: @zindex-tooltip;
   display: block;
   visibility: visible;
-  // Reset font and text propertes given new insertion method
+  // Reset font and text properties given new insertion method
   font-family: @font-family-base;
   font-size: @font-size-small;
   font-weight: normal;