Doc test: use propery regex for file size
Doc test: use propery regex for file size

The _cat/shards docs asserted that one of the columns looked like
a propery byte size but used a regex like `\d+\.\d+.*` which doesn't
match `0b` which is a possible value. Instead this uses
`\d(\.\d+)?[kmg]?b`.

strapdata/elassandra5-rc,strapdata/elassandra5-rc,strapdata/elassandra5-rc,strapdata/elassandra5-rc,strapdata/elassandra5-rc