Improve docs

I made a number of minor changes to improve the readme:

 ◦ "i18n" should be lowercase
 ◦ "software" is already plural so no need to add an "s"
 ◦ comma should only be used before "and" with a list of items greater than two:
   "foo, bar, and baz" but "foo and bar"
 ◦ "both foo or bar" should either by "both foo and bar" or "either foo or bar",
   so I used the former
 ◦ "Node.js" should be titlecase
 ◦ "Attention" typo
 ◦ pronoun "its" should be "their" b/c the subject is plural "libraries"
 ◦ changed "some" to "several" b/c it sounds more natural

Signed-off-by: Nick Patch <patch@cpan.org>

Closes #25