Add disallowpubkey

Author: Jon Staab

86.md

@@ -40,6 +40,9 @@ This is the list of **methods** that may be supported:
 * `allowpubkey`:
   - params: `["<32-byte-hex-public-key>", "<optional-reason>"]`
   - result: `true` (a boolean always set to `true`)
+* `disallowpubkey`:
+  - params: `["<32-byte-hex-public-key>", "<optional-reason>"]`
+  - result: `true` (a boolean always set to `true`)
 * `listallowedpubkeys`:
   - params: `[]`
   - result: `[{"pubkey": "<32-byte-hex>", "reason": "<optional-reason>"}, ...]`, an array of objects