Add clarification of semantics of 0x00 hash type

Author: AdamISZ

bip-taproot.mediawiki

@@ -100,7 +100,7 @@ The following rules apply:
 
 ==== hash_type ====
 
-<code>hash_type</code> is an 8-bit unsigned value. The <code>SIGHASH</code> encodings from the legacy script system are used, including <code>SIGHASH_ALL</code>, <code>SIGHASH_NONE</code>, <code>SIGHASH_SINGLE</code>, and <code>SIGHASH_ANYONECANPAY</code>
+<code>hash_type</code> is an 8-bit unsigned value. The <code>SIGHASH</code> encodings from the legacy script system are used, including <code>SIGHASH_ALL</code>, <code>SIGHASH_NONE</code>, <code>SIGHASH_SINGLE</code>, and <code>SIGHASH_ANYONECANPAY</code>. Use of the default <code>hash_type = 0x00</code> results in signing over the whole transaction just as for <code>SIGHASH_ALL</code>.
 
 The following use of <code>hash_type</code> are invalid, and fail execution: