Add right border bar to Dark and Light theme

Ayu has it. Adding similar rule to other themes makes users less
surprised and makes GUI more consistent.

Author: tesuji

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

@@ -270,6 +270,7 @@ a.test-arrow:hover{
 
 :target > code, :target > .in-band {
 	background-color: #494a3d;
+	border-right: 3px solid #bb7410;
 }
 
 pre.compile_fail {

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

@@ -265,6 +265,7 @@ a.test-arrow:hover{
 
 :target > code, :target > .in-band {
 	background: #FDFFD3;
+	border-right: 3px solid #ffb44c;
 }
 
 pre.compile_fail {