statistics: Clarify that year specifies since when providers are avai…

…lable/listed

themes/xmpp-providers/layouts/shortcodes/statistics.html

@@ -23,7 +23,7 @@ <h5>Provider Categories</h5>
     <div class="col mx-auto text-center">
         <div class="bg-body-tertiary rounded p-3">
             <h5>History of Providers</h5>
-            <small class="text-muted">This chart shows since when providers are available.</small>
+            <small class="text-muted">This chart shows since when providers are available or listed.</small>
             <div id="since_bar_chart_container" style="height:400px;"
                 data-values="{{ .Site.Data.statistics.since_bar_chart_data | jsonify }}"></div>
         </div>