fix: set anchor color to white on admonitions

src/css/custom.css

@@ -41,6 +41,10 @@ p a {
   color: var(--ifm-color-warning);
 }
 
+.theme-admonition a {
+  color: var(--ifm-color-white);
+}
+
 /* FORM & INPUT */
 form > p {
   font-size: small;