docs: use #343 as an example of a good PR for dictionary edits

packages/web/src/routes/docs/contributors/dictionary/+page.md

@@ -6,6 +6,8 @@ The curated dictionary is the English dictionary Harper uses as reference intern
 It is common, especially with technical language, to come across words that are not in this dictionary.
 If this happens to you, please open a PR to get it in.
 
+PR [#343](https://github.com/Automattic/harper/pull/343) is a great example of what is described here.
+
 There are two files you need to worry about.
 [`harper-core/dictionary.dict`](https://github.com/Automattic/harper/blob/master/harper-core/dictionary.dict) and [`harper-core/affixes.json`](https://github.com/Automattic/harper/blob/master/harper-core/affixes.json).
 The first is a list of words, tagged with modifiers defined in the second.