Fix more <a> color

Author: GuillaumeGomez

src/librustdoc/html/static/css/themes/ayu.css

@@ -218,6 +218,8 @@ a {
 }
 a.srclink,
 a#toggle-all-docs,
+a.anchor,
+.section-header a,
 #source-sidebar a,
 pre.rust a,
 .sidebar a,

src/librustdoc/html/static/css/themes/dark.css

@@ -180,6 +180,8 @@ a {
 }
 a.srclink,
 a#toggle-all-docs,
+a.anchor,
+.section-header a,
 #source-sidebar a,
 pre.rust a,
 .sidebar a,

src/librustdoc/html/static/css/themes/light.css

@@ -175,6 +175,8 @@ a {
 }
 a.srclink,
 a#toggle-all-docs,
+a.anchor,
+.section-header a,
 #source-sidebar a,
 pre.rust a,
 .sidebar a,