Change ToC script to use <br> instead of trailing spaces

Also updated docs that contain ToC. Fixes #1048

docs/slow-compiles.md

@@ -1,11 +1,11 @@
 <a id="top"></a>
 # Why do my tests take so long to compile?
 
-**Contents**  
-[Short answer](#short-answer)  
-[Long answer](#long-answer)  
-[Practical example](#practical-example)  
-[Other possible solutions](#other-possible-solutions)  
+**Contents**<br>
+[Short answer](#short-answer)<br>
+[Long answer](#long-answer)<br>
+[Practical example](#practical-example)<br>
+[Other possible solutions](#other-possible-solutions)<br>
 
 Several people have reported that test code written with Catch takes much longer to compile than they would expect. Why is that?