Document two categorization processes in a footer

The wording, of course, is negotiable.  Personally I like the style of
"[Condition one might be in]? [How to get oneself out of it]!".

Signed-off-by: Kristofer Rye <[email protected]>

Author: rye

app/templates/categories.hbs

@@ -60,3 +60,11 @@
 </div>
 
 <Pagination @pages={{this.pages}} @prevPage={{this.prevPage}} @nextPage={{this.nextPage}} />
+
+<div class='categories-footer'>
+  Got an idea for another category?
+  <a href='https://github.com/rust-lang/crates.io/blob/master/src/boot/categories.toml#L1-L3'>Suggest it!</a>
+  &bull;
+  Want to categorize your crate?
+  <a href='http://doc.crates.io/manifest.html#package-metadata'>Add metadata!</a>
+</div>