Doc string of FIRST++

[rebolbot]

Submitted by: Ladislav

The WORD parameter help string is incompatible with other similar argument help strings (FORSKIP).

My proposal is to change the help string to:

    'word [word!] "Word must refer to a series"

>> source first+
first+: make native! [[
    {Return FIRST of series, and increment the series index.}
    'word [word!] "Word must be a series"
]]

^{CC - Data [ Version: r3 master Type: Bug Platform: All Category: Documentation Reproduce: Always Fixed-in:none ]}

[rebolbot]

Submitted by: BrianH

While you're at it, change the top doc string to "Return the FIRST of a series then increment the series index.". We have enough doc string length available in this case for better grammar.

[rebolbot]

Submitted by: Ladislav

Pull request submitted