[ja] Minor wording improvement(textui command-line option)

@m-takagi 

[ja] Fixes "switches" to "option" in 3.7 - 4.6.

ref. 
version 3.6
`Command-Line Switches`
https://phpunit.de/manual/3.6/en/textui.html#textui.clioptions

version 3.7 later
`Command-Line Options`
https://phpunit.de/manual/3.7/en/textui.html#textui.clioptions