Updated CSS Selector help (markdown)

CSS-Selector-help.md

@@ -15,3 +15,16 @@ So for example if the HTML is
 ```
 
 the selector would be `.points #interesting`
+
+# Select/extract just the HREF from `<A>` tag using xpath
+
+if you have
+```
+<h3>
+  <a href..></a>
+</h3>
+```
+
+filter: `//h3/parent::a//@href`
+
+