Fix BIP 48 headers and add to README

Author: luke-jr

README.mediawiki

@@ -258,6 +258,13 @@ Those proposing changes should consider that ultimately consent may rest with th
 | Justus Ranvier
 | Informational
 | Draft
+|- style="background-color: #ffffcf"
+| [[bip-0048.mediawiki|48]]
+| Applications
+| Multi-Script Hierarchy for Multi-Sig Wallets
+| Fontaine
+| Standard
+| Proposed
 |- style="background-color: #cfffcf"
 | [[bip-0049.mediawiki|49]]
 | Applications

bip-0048.mediawiki

@@ -1,14 +1,14 @@
 <pre>
-  BIP: ?
+  BIP: 48
   Layer: Applications
   Title: Multi-Script Hierarchy for Multi-Sig Wallets
   Author: Fontaine <[email protected]>
   Comments-Summary: No comments
-  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-?
+  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0048
   Status: Proposed
   Type: Standards Track
   Created: 2020-12-16
-  License: MIT License
+  License: MIT
 </pre>
 
 ==Abstract==