Correct spelling mistakes. (#24778)

scss/_custom-forms.scss

@@ -153,7 +153,7 @@
 
     &::-ms-value {
       // For visual consistency with other platforms/browsers,
-      // supress the default white text on blue background highlight given to
+      // suppress the default white text on blue background highlight given to
       // the selected option text when the (still closed) <select> receives focus
       // in IE and (under certain conditions) Edge.
       // See https://github.com/twbs/bootstrap/issues/19398.

scss/_functions.scss

@@ -63,7 +63,7 @@
   }
 }
 
-// Retreive color Sass maps
+// Retrieve color Sass maps
 @function color($key: "blue") {
   @return map-get($colors, $key);
 }