Update HKDF documentation

Author: ektrah

docs/api/nsec.cryptography.keyderivationalgorithm.md

@@ -132,6 +132,9 @@ An array of bytes that contains the derived bytes.
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]
@@ -195,6 +198,9 @@ bytes
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]
@@ -270,6 +276,9 @@ A new instance of the [[Key|Key Class]] class that represents the derived key.
 ArgumentNullException
 : `sharedSecret` or `algorithm` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]

docs/api/nsec.cryptography.keyderivationalgorithm2.md

@@ -159,6 +159,9 @@ An array of bytes that contains the derived bytes.
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]
@@ -224,6 +227,9 @@ bytes
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]
@@ -301,6 +307,9 @@ A new instance of the [[Key|Key Class]] class that represents the derived key.
 ArgumentNullException
 : `sharedSecret` or `algorithm` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm Class#MinSaltSize]]
@@ -347,6 +356,9 @@ An array of bytes that contains the extracted pseudorandom key.
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm2 Class#MinSaltSize]]
@@ -392,6 +404,9 @@ pseudorandomKey
 ArgumentNullException
 : `sharedSecret` is `null`.
 
+ArgumentException
+: `inputKeyingMaterial` is empty.
+
 ArgumentException
 : `salt.Length` is less than
     [[MinSaltSize|KeyDerivationAlgorithm2 Class#MinSaltSize]]