Remove "throws InvalidEscapeException" from StringContext.raw doc

Since StringContext.raw doesn't escape its input, it does not call `treatEscapes` and cannot throw the InvalidEscapeException.
Fixed incorrect example in StringContext.raw doc

As pointed out by @som-snytt, \u0023 is #, not \u0025.
Merge pull request #3890 from dhgarrette/2.11.x

Remove "throws InvalidEscapeException" from StringContext.raw doc