fix: Support description markdown and longer length (#385)

Fixes https://github.com/webrecorder/replayweb.page/issues/381

## Changes

- Renders description as markdown
- Shows "Collection name" and "About this collection" labels when
description is present
- Fixes overflow issue where bottom few pixels of embed is cut off
- Hides description in mobile view

Co-authored-by: emma <hi@emma.cafe>

package.json

@@ -27,6 +27,8 @@
     "keyword-mark-element": "^0.2.0",
     "lit": "3.1.1",
     "marked": "^4.0.10",
+    "micromark": "^4.0.1",
+    "micromark-extension-gfm-strikethrough": "^2.1.0",
     "mime-types": "^2.1.32",
     "minimist": "^1.2.5",
     "node-fetch": "^3.3.0",