docs: image migration guide for vuepress (#799)

docs/guide/migration-from-vuepress.md

@@ -1,3 +1,24 @@
 # Migration from VuePress
 
-Coming soon...
+## Markdown
+
+### Images
+
+Unlike VuePress, VitePress handles [`base`](/guide/asset-handling.html#base-url) of your config automatically when you use static image.
+
+Hence, now you can render images without `img` tag.
+
+```diff
+- <img :src="$withBase('/foo.png')" alt="foo">
++ ![foo](/foo.png)
+```
+
+::: warning
+For dynamic images you still need `withBase` as shown in [Base URL guide](/guide/asset-handling.html#base-url).
+:::
+
+Use `<img.*withBase\('(.*)'\).*alt="([^"]*)".*>` regex to find and replace it with `![$2]($1)` to replace all the images with `![](...)` syntax.
+
+---
+
+more to follow...