Update _summary-list.scss

[PR alphagov#1169](alphagov#1169) added in some CSS:
- ``word-break: break-word;``, followed by
- ``word-break: break-all;``

``word-break: break-word;`` is the favoured behaviour, but isn't fully supported.  
``word-break: break-all;`` is the fallback behaviour, it sometimes results in unfavourable wrapping mid-word.  

The order for this CSS needs to be changed to, otherwise the less favourable `break-all` takes precedence.
```CSS
word-break: break-all;
word-break: break-word;
```

**caniuse** said:
> Chrome, Safari and other WebKit/Blink browsers also support the unofficial break-word value

The implication here being that it is not fully supported, so ``word-break: break-all;`` is still needed as a fallback.

Discussed with [Colin Rotherham](https://github.com/colinrotherham)

src/components/summary-list/_summary-list.scss

@@ -58,8 +58,8 @@
   .govuk-summary-list__value {
     // sass-lint:disable no-duplicate-properties
     // Automatic wrapping for unbreakable text (e.g. URLs)
-    word-break: break-word; // WebKit/Blink only
     word-break: break-all; // Standards
+    word-break: break-word; // Chrome/Safari/WebKit/Blink only
   }
 
   .govuk-summary-list__key {