Switch alt for aria-label for graphs as more appropriate for content

src/App.vue

@@ -59,8 +59,8 @@ export default {
       </div>
     </div>
     <div class="bottom-section">
-      <MultiLineChart alt="NPK data line graph" v-if="npkData" :chart-data="npkData" :x-axis-data=pastSevenDaysData />
-      <MultiAxisChart alt="Temperature Humidity Moisture data line multi-axis graph" v-if="thmData" :chart-data="thmData"
+      <MultiLineChart aria-label="NPK data line graph" v-if="npkData" :chart-data="npkData" :x-axis-data=pastSevenDaysData />
+      <MultiAxisChart aria-label="Temperature Humidity Moisture data line multi-axis graph" v-if="thmData" :chart-data="thmData"
         :x-axis-data=pastSevenDaysData />
     </div>
   </div>