Merge pull request #2214 from murchandamus/bip47-touch-ups

bip47: 
- Change BIP type from Informational to Specification
- Move "recent changes" from above preamble to Changelog section
- Drop Comments headers from Preamble

README.mediawiki

@@ -279,7 +279,7 @@ users (see also: [https://en.bitcoin.it/wiki/Economic_majority economic majority
 | Applications
 | Reusable Payment Codes for Hierarchical Deterministic Wallets
 | Justus Ranvier
-| Informational
+| Specification
 | Deployed
 |- style="background-color: #cfffcf"
 | [[bip-0048.mediawiki|48]]