Generates an anchor for a markdown header.
var anchor = require('anchor-markdown-header');
anchor('"playerJoined" (player)');
// --> ["playerJoined" (player)](#playerjoined-player)
anchor('fs.rename(oldPath, newPath, [callback])', 'nodejs.org', 'fs')
// --> [fs.rename(oldPath, newPath, [callback])](#fs_fs_rename_oldpath_newpath_callback)
// github.com mode is default
anchor('"playerJoined" (player)') === anchor('"playerJoined" (player)', 'github.com');
// --> true
anchor(header[, mode] [, moduleName] [, repetition)
/**
* @name anchorMarkdownHeader
* @function
* @param header {String} The header to be anchored.
* @param mode {String} The anchor mode ('github.com'|'nodejs.org|bitbucket.org').
* @param repetition {Number} The nth occurrence of this header text, starting with 0. Not required for the 0th instance.
* @param moduleName {String} The name of the module of the given header (required only for 'nodejs.org' mode).
* @return {String} The header anchor that is compatible with the given mode.
*/