update language around tlds and introduce nonTldPrefixes

SIPS/sip-12.md

@@ -51,14 +51,18 @@ This permission is specified as follows in `snap.manifest.json` files:
   "initialPermissions": {
     "endowment:name-lookup": {
         "chains": ["eip155:1", "bip122:000000000019d6689c085ae165831e93"],
-        "tlds": [".lens"],
+        "matchers": { "tlds": ["lens"], "nonTldPrefixes": ["farcaster"] }
     }
   }
 }
 ```
 
 `chains` - A non-empty array of CAIP-2 chain IDs that the snap supports. This field is useful for a client in order to avoid unnecessary overhead.
-`tlds` - A non-empty array of top level domains that the snap will provide resolution for. This field is useful for a client for validating input for domain resolution, also helpful in reducing overhead.
+`matchers` - A non-empty object that MUST contain 1 or both of the below properties. These matchers are useful for a client for validating input for domain resolution, also helpful in reducing overhead. 
+  `tlds` - An optional non-empty array of top level domains that the snap will provide resolution for.
+  `nonTldPrefixes` - An optional non-empty array of prefixes that the snap expects for non-tld domain lookup.
+
+**Note:** Tld domains are presumed to end with "." and one of the `tlds`. Non-tld domains are presumed to start with one of the `nonTldPrefixes` followed by ":" then the domain. Respectively, an example of each would be `hassan.lens` and `farcaster:hbm88`.  
 
 ### Snap Implementation