slip-0039: explain the index/threshold table in one sentence, add bip32 reference

slip-0039.md

@@ -45,7 +45,7 @@ From this value, every byte is mapped to the specified field in a little-endian
 
 The index corresponds to the SSSS part's `x` value (see the diagram above) and the SSSS part is the corresponding `y` value.
 
-Index and threshold are encoding using the following scheme:
+Index and threshold are encoding using the following scheme (convert from bits to decimal and add 1):
 
 | 5-bit value | index/threshold value |
 |-------------|-----------------------|
@@ -82,6 +82,8 @@ Passphrase should contain only ASCII characters to achieve the best interoperabi
 
 We will use `PBKDF2(PRF = HMAC-SHA256, Password = master_secret, Salt = "SLIP0039" + passphrase, iterations = 20000, dkLen = 256 bits)` as the key derivation function.
 
+We suggest to use the obtained seed as a master seed `S` for Hierarchical Deterministic Wallets described in BIP-0032.
+
 ## Versioning
 
 Our scheme doesn't support versioning. This is intentional to avoid unclear claims such as SLIP-0039 compatibility without a clear understanding, which version of the scheme is actually meant.
@@ -105,4 +107,5 @@ TBD
 
 ## References
 
+* [BIP-0032: Hierarchical Deterministic Wallets](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki)
 * [Secret Sharing Step by Step by Point Software](http://www.pointsoftware.ch/en/secret-sharing-step-by-step/)