Add note for fosshost instance [skip ci]

The fosshost team decommissioned the region that Whoogle was hosted in,
but hasn't provided an option to transfer the domain record to the new VM. Until
that is fixed, the instance is inaccessible.

README.md

@@ -512,7 +512,7 @@ A lot of the app currently piggybacks on Google's existing support for fetching
 
 | Website | Country | Language | Cloudflare |
 |-|-|-|-|
-| [https://whoogle.fossho.st](https://whoogle.fossho.st) | 🇺🇸 US | Multi-choice | |
+| [https://whoogle.fossho.st](https://whoogle.fossho.st) (down until further notice) | 🇺🇸 US | Multi-choice | |
 | [https://search.albony.xyz](https://search.albony.xyz/) | 🇮🇳 IN | Multi-choice |  |
 | [https://whoogle.sdf.org](https://whoogle.sdf.org) | 🇺🇸 US | Multi-choice |
 | [https://search.garudalinux.org](https://search.garudalinux.org) | 🇩🇪 DE | Multi-choice |  |