CodeBlockComponent: F# closing endregion comment tag included in rendered text.

[JeffreySax]

This is similar to #428 but for F#.

F# does not have region directives. It uses // for end-of-line comments and (* *) for delimited comments.

Given MAML

<code language="f#" source="code.fs" region="sample" />

and the F# code in code.fs:

// #region sample
let x = 1
// #endregion

this renders:

let x = 1
//