Convert comments on function examples to /** */ style

[stonemaster]

As phobos does it all comments should have the /** and */ syntax for comments.

[wilzbach]

There are also a couple of other Phobos style guidelines - like Allman braces Or spaces between import selections etc that we should look for and be consistent. Ideally we should run Dscanner on our code samples.

[wilzbach]

This issue was moved to dlang-tour/english#47