seedminer: use old stub text

While Seedminer is now deprecated, it has been a page on the guide for
more than 5 years, so it's guaranteed to be linked basically everywhere.

So instead, let's stub this.

_pages/en_US/seedminer.txt

@@ -2,7 +2,5 @@
 title: "Seedminer"
 ---
 
-The era of Seedminer is over, for now... [MSET9](installing-boot9strap-(mset9)) can be used on all firmwares Seedminer was previously used on, and is quicker and less resource-intensive overall. If you really need the instructions, check out the [wiki page](https://wiki.hacks.guide/wiki/3DS:Seedminer/BFM) for it.
-
-### Return to the [Index page](index)
-{: .notice--primary}
+This page has been removed because the method used is outdated. Please follow a modern method linked on the [Get Started](get-started) page.
+{: .notice--warning}