Add $navicon-link-color-hover 1/2 (mmistakes#1089)

Since the orig color-scheme doesn't always represent the nav/site colors

Author: palatinux

_sass/minimal-mistakes/_variables.scss

@@ -96,7 +96,7 @@ $link-color-hover           : mix(#000, $link-color, 25%) !default;
 $link-color-visited         : mix(#fff, $link-color, 25%) !default;
 $masthead-link-color        : $primary-color !default;
 $masthead-link-color-hover  : mix(#000, $primary-color, 25%) !default;
-
+$navicon-link-color-hover   : mix(#fff, $primary-color, 75%) !default;
 
 /*
    Breakpoints
@@ -126,4 +126,4 @@ $border-radius              : 4px !default;
 $box-shadow                 : 0 1px 1px rgba(0, 0, 0, 0.125) !default;
 $navicon-width              : 1.5rem !default;
 $navicon-height             : 0.25rem !default;
-$global-transition          : all 0.2s ease-in-out !default;
+$global-transition          : all 0.2s ease-in-out !default;