Make alt text more friendly when custom reaction doesn't have shortcode

Signed-off-by: Sumner Evans <sumner@beeper.com>

Author: sumnerevans

src/components/views/messages/ReactionsRowButton.tsx

@@ -148,7 +148,7 @@ export default class ReactionsRowButton extends React.PureComponent<IProps, ISta
                 reactionContent = (
                     <img
                         className="mx_ReactionsRowButton_content"
-                        alt={customReactionName || content}
+                        alt={customReactionName || _t("Custom reaction")}
                         src={imageSrc}
                         width="16"
                         height="16"

src/i18n/strings/en_EN.json

@@ -2483,6 +2483,7 @@
     "Add reaction": "Add reaction",
     "Reactions": "Reactions",
     "%(reactors)s reacted with %(content)s": "%(reactors)s reacted with %(content)s",
+    "Custom reaction": "Custom reaction",
     "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>": "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>",
     "Message deleted on %(date)s": "Message deleted on %(date)s",
     "%(senderDisplayName)s changed the avatar for %(roomName)s": "%(senderDisplayName)s changed the avatar for %(roomName)s",