Add buttons.

ui/src/components/markdown-textarea.tsx

@@ -187,6 +187,24 @@ export class MarkdownTextArea extends Component<
                 <use xlinkHref="#icon-italic"></use>
               </svg>
             </button>
+            <button
+              class="btn btn-sm text-muted"
+              data-tippy-content={i18n.t('subscript')}
+              onClick={linkEvent(this, this.handleInsertSubscript)}
+            >
+              <svg class="icon icon-inline">
+                <use xlinkHref="#icon-subscript"></use>
+              </svg>
+            </button>
+            <button
+              class="btn btn-sm text-muted"
+              data-tippy-content={i18n.t('superscript')}
+              onClick={linkEvent(this, this.handleInsertSuperscript)}
+            >
+              <svg class="icon icon-inline">
+                <use xlinkHref="#icon-superscript"></use>
+              </svg>
+            </button>
             <button
               class="btn btn-sm text-muted"
               data-tippy-content={i18n.t('link')}

ui/translations/en.json

@@ -53,6 +53,8 @@
     "archive_link": "archive link",
     "bold": "bold",
     "italic": "italic",
+    "subscript": "subscript",
+    "superscript": "superscript",
     "header": "header",
     "strikethrough": "strikethrough",
     "quote": "quote",