ShExC grammar for comment has extraneous `| '\\/')`

[ericprud]

http://shex.io/shex-semantics/#term-PASSED_TOKENS says (see table at bottom 'cause markdown is being weird).

On the last line, this clause is not needed: `| '\\/')`.

Demo'd using PCRE as implemented in node javascript:

> console.log("ab/*c*\\/d*/ef")
ab/*c*\/d*/ef
undefined
> "ab/*c*\\/d*/ef".match(/\/\*((?:[^*]|\*[^/])*)\*\//)
[
  '/*c*\\/d*/',
  'c*\\/d',
  index: 2,
  input: 'ab/*c*\\/d*/ef',
  groups: undefined
]

[98]

PASSED TOKENS

::=

[ \t\r\n]+ | "#" [^\r\n]* | "/*" ([^*] | '*' ([^/] | '\\/'))* "*/"