Describe serialisation format very fully/formally.
Separate example from 'sum' options.

...to make it clear that the example is of an ideal root, not a root using a shorter sum.
Set good example: give dummy account balance 8dp.
s/interior/internal/g for consistency.

Also add subheaders for leaf/internal hashing to give that otherwise dense
section some landmarks.
Fix internal links, define "root path".
s/nearest power of two/next power of two/

You can't pad a list and make it smaller :)
Remove unnecessary brackets from regex.
Explicitly state lowercase hex for hash/nonce.
Use shortest balance, prefer whole subunits.

Use the shortest possible string representation of `balance`.

Soften Bitcoin-specific 'MUST' for decimal places to a currency-neutral SHOULD,
and prefer rounding before adding/converting to string/hashing/serialisation.
Be explicit: round subunits before adding balances.
Fix hashing examples to comply with balance change.

Also be explicit that child hashes used when hashing internal nodes are also
"64-digit hexadecimal string with lowercase letters", for consistency with JSON
below, and take the opportunity to sneak in a concrete example hash with
leading zeros.
More consistency fixes.  Add node_data examples.

Also say explicitly that `"data": {}` can and should be dropped.
Merge pull request #18 from zw/master

 Describe serialisation format very fully/formally