Prometheus: Update capitalisation of elements (#65724)

* update capitalization of elements

* fix tests

public/app/plugins/datasource/prometheus/querybuilder/components/MetricEncyclopediaModal.test.tsx

@@ -22,7 +22,7 @@ describe('MetricEncyclopediaModal', () => {
   it('renders the modal', async () => {
     setup(defaultQuery, listOfMetrics);
     await waitFor(() => {
-      expect(screen.getByText('Browse Metrics')).toBeInTheDocument();
+      expect(screen.getByText('Browse metrics')).toBeInTheDocument();
     });
   });
 

public/app/plugins/datasource/prometheus/querybuilder/components/MetricEncyclopediaModal.tsx

@@ -485,7 +485,7 @@ export const MetricEncyclopediaModal = (props: Props) => {
     <Modal
       data-testid={testIds.metricModal}
       isOpen={isOpen}
-      title="Browse Metrics"
+      title="Browse metrics"
       onDismiss={onClose}
       aria-label="Metric Encyclopedia"
       className={styles.modal}

public/app/plugins/datasource/prometheus/querybuilder/components/PromQueryBuilder.tsx

@@ -221,7 +221,7 @@ export const PromQueryBuilder = React.memo<Props>((props) => {
               size="sm"
               onClick={() => setMetricEncyclopediaModalOpen((prevValue) => !prevValue)}
             >
-              Metric Encyclopedia
+              Metric encyclopedia
             </Button>
             {query.metric && (
               <Tag