RND-548: add subscript and superscript support (#3110)

Author: BrettJephson

.changeset/hungry-candles-sing.md

@@ -0,0 +1,5 @@
+---
+"gitbook": patch
+---
+
+Add superscript and subscript text rendering

packages/gitbook/src/components/DocumentView/Text.tsx

@@ -5,6 +5,8 @@ import type {
     DocumentMarkItalic,
     DocumentMarkKeyboard,
     DocumentMarkStrikethrough,
+    DocumentMarkSubscript,
+    DocumentMarkSuperscript,
     DocumentText,
     DocumentTextMark,
 } from '@gitbook/api';
@@ -47,10 +49,8 @@ const MARK_STYLES = {
     strikethrough: Strikethrough,
     color: Color,
     keyboard: Keyboard,
-
-    // TODO: add support for these marks
-    subscript: null,
-    superscript: null,
+    superscript: Superscript,
+    subscript: Subscript,
 };
 
 interface MarkedLeafProps<Mark extends DocumentTextMark> {
@@ -78,6 +78,14 @@ function Keyboard(props: MarkedLeafProps<DocumentMarkKeyboard>) {
     );
 }
 
+function Superscript(props: MarkedLeafProps<DocumentMarkSuperscript>) {
+    return <sup>{props.children}</sup>;
+}
+
+function Subscript(props: MarkedLeafProps<DocumentMarkSubscript>) {
+    return <sub>{props.children}</sub>;
+}
+
 function Code(props: MarkedLeafProps<DocumentMarkCode>) {
     return (
         <code