[R2] Fix footnote number in limits.mdx (#18435)

Author: tojapawel

src/content/docs/r2/platform/limits.mdx

@@ -21,7 +21,7 @@ import { Render } from "~/components";
 and configuring buckets.
 <br /> <sup>2</sup> The object size limit is 5 GiB less than 5 TiB, so 4.995
 TiB.
-<br /> <sup>2</sup> The max upload size is 5 MiB less than 5 GiB, so 4.995 GiB.
+<br /> <sup>3</sup> The max upload size is 5 MiB less than 5 GiB, so 4.995 GiB.
 <br /> <sup>4</sup> Max upload size applies to uploading a file via one request,
 uploading a part of a multipart upload, or copying into a part of a multipart
 upload. If you have a Worker, its inbound request size is constrained by