Add some documentation to Alphabet.

Author: wyhaines

src/base58/alphabet.cr

@@ -2,21 +2,25 @@ module Base58
   # This is the base class for Base58 Alphabet implementations. It is not intended to be used directly.
   class Alphabet
     macro inherited
+      # Query the base58 alphabet for the digit/character that represents the given value.
       @[AlwaysInline]
       def self.[](val)
         BaseToUInt[val]
       end
 
+      # Query the base58 alphabet for the digit/character that represents the given value. Returns nil if the value is not in the alphabet.
       @[AlwaysInline]
       def self.[]?(val)
         BaseToUInt[val]?
       end
 
+      # Query the base58 alphabet for the value that the given digit/character represents.
       @[AlwaysInline]
       def self.inverse(val)
         UIntToBase[val]
       end
 
+      # Query the base58 alphabet for the value that the given digit/character represents. Returns nil if the digit/character is not in the alphabet.
       @[AlwaysInline]
       def self.inverse?(val)
         byte = UIntToBase[val]?