Doc tweaks.

Readme.md

@@ -17,7 +17,7 @@ To get the Base30 encoding of the number 412:
 result, err := basexx.Digits(412, basexx.Base30)
 ```
 
-To decode the base30 digit string `"fr"`:
+To decode the Base30 digit string `"fr"`:
 
 ```go
 result, err := basexx.Value("fr", basexx.Base30)

basexx.go

@@ -59,8 +59,11 @@ var zero = new(big.Int)
 // Convert converts the digits of src, writing them to dest.
 // Both src and dest specify their bases.
 // Return value is the number of digits written to dest (even in case of error).
+//
 // This function consumes all of src before producing any of dest,
 // so it may not be suitable for input streams of arbitrary length.
+// In particular,
+// do not expect to be able to use it for encoding byte streams the way you can with e.g. encoding/base64.
 func Convert(dest Dest, src Source) (int, error) {
 	var (
 		accum    = new(big.Int)

buffer.go

@@ -13,6 +13,11 @@ type Buffer struct {
 }
 
 // NewBuffer produces a Buffer from the given byte slice described by the given Base.
+//
+// When the Buffer is to be used as a Dest in a call to Convert,
+// the supplied []byte must have length >= Length(from, base.N(), digits)
+// where `from` is the base you're converting from
+// and `digits` is the number of digits being converted.
 func NewBuffer(buf []byte, base Base) *Buffer {
 	return &Buffer{
 		buf:  buf,