Fix reading year nav bar now we're 5yrs+

Bar was too wide for mobile view, so let's simply it

_data/books.json

@@ -1,4 +1,20 @@
 [
+  {
+    "title": "Not the end of the world",
+    "authors": [
+      "Hannah Richie"
+    ],
+    "work_iri": "https://www.wikidata.org/wiki/",
+    "edition_iri": "https://www.wikidata.org/wiki/"
+  },
+  {
+    "title": "Cinema Speculation",
+    "authors": [
+      "Quentin Tarintio"
+    ],
+    "work_iri": "https://www.wikidata.org/wiki/",
+    "edition_iri": "https://www.wikidata.org/wiki/"
+  },
   {
     "title": "Wilding",
     "subtitle": "The return of nature to a British far",

_data/navigation.json

@@ -16,8 +16,6 @@
   "book_years": [
     "2024",
     "2023",
-    "2022",
-    "2021",
-    "2020"
+    "2022"
   ]
 }

_includes/book_list_nav.html

@@ -5,5 +5,8 @@
       <a {% if year==page.year %} class="active" {% endif %} href="/reading/{{year}}">{{year}}</a>
     </li>
     {% endfor %}
+    <li>
+      <a href="/reading#2021">older</a>
+    </li>
   </ul>
 </nav>

reading.html

@@ -8,7 +8,7 @@
 {% assign finished_books_by_year = finished_books | group_by_exp:"book", "book.date_finished | date: '%Y'" %}
 {% for year in finished_books_by_year %}
 
-<h2>{{ year.name }}</h2>
+<h2 id="{{year.name}}">{{ year.name }}</h2>
 <ul>
   {% for book in year.items %}
   <li>