fix: update to provide for future extensibility

Author: Fonta1n3

bip-0048.mediawiki

@@ -23,7 +23,8 @@ This BIP is a particular application of BIP43.
 
 The motivation of this BIP is to define the existing industry wide practice of utilizing  m/48'
 derivation paths in hierarchical deterministic multi-sig wallets so that other developers may
-benefit from a standard.
+benefit from a standard. This BIP allows for future script types to easily be appended to the
+specification so that a new BIP is not required for every future script type.
 
 The hierarchy proposed in this paper is quite comprehensive. It allows the handling of
 multiple accounts, external and internal chains per account, multiple script types and
@@ -84,15 +85,22 @@ Hardened derivation is used at this level.
 ===Script===
 
 This level splits the key space into two separate <code>script_type</code>(s). To provide
-backward compatibility.
+forward compatibility for future script types this specification can be easily extended.
 
-The recommended default is pay to witness script hash <code>m/48'/0'/0'/2'</code>.
-
-The following represent mainnet, account 0:
+Currently the only script types covered by this BIP are Native Segwit (p2wsh) and
+Nested Segwit (p2sh-p2wsh).
 
+The following path represents Nested Segwit (p2sh-p2wsh) mainnet, account 0:
 <code>1'</code>: Nested Segwit (p2sh-p2wsh) <code>m/48'/0'/0'/1'</code></br>
+
+The following paths represent Native Segwit (p2wsh) mainnet, account 0:
 <code>2'</code>: Native Segwit (p2wsh) <code>m/48'/0'/0'/2'</code></br>
 
+The recommended default for wallets is pay to witness script hash <code>m/48'/0'/0'/2'</code>.
+
+To add new script types submit a PR to this specification and include it in the list above:
+<code>X'</code>: Future script type <code>m/48'/0'/0'/X'</code></br>
+
 ===Change===
 
 Constant 0 is used for external chain and constant 1 for internal chain (also