Fixes #13943: Lighten the navbar inverse link color more since our text contrast change in v3.2.0

dist/css/bootstrap.css

@@ -4218,7 +4218,7 @@ fieldset[disabled] .navbar-default .btn-link:focus {
   background-color: transparent;
 }
 .navbar-inverse .navbar-text {
-  color: #777;
+  color: #969696;
 }
 .navbar-inverse .navbar-nav > li > a {
   color: #777;

docs/dist/css/bootstrap.css

@@ -4218,7 +4218,7 @@ fieldset[disabled] .navbar-default .btn-link:focus {
   background-color: transparent;
 }
 .navbar-inverse .navbar-text {
-  color: #777;
+  color: #969696;
 }
 .navbar-inverse .navbar-nav > li > a {
   color: #777;

less/variables.less

@@ -368,7 +368,7 @@
 
 // Inverted navbar
 // Reset inverted navbar basics
-@navbar-inverse-color:                      @gray-light;
+@navbar-inverse-color:                      lighten(@gray-light, 12%);
 @navbar-inverse-bg:                         #222;
 @navbar-inverse-border:                     darken(@navbar-inverse-bg, 10%);