Switch gulp docs to build its output using documentation.js (#1545)

* Use 'gulp-documentation' instead of jsdoc2md

* Build Markdown instead (more versatile)

* Update package.json per review feedback

Specifically:

- Alphabetize list of deps
- Prepend "^" to package versions

* Update yarn.lock alongside package.json

gulpfile.js

@@ -16,7 +16,7 @@ var opens = require('open');
 var webpackConfig = require('./webpack.conf');
 var helpers = require('./gulpHelpers');
 var del = require('del');
-var gulpJsdoc2md = require('gulp-jsdoc-to-markdown');
+var gulpDocumentation = require('gulp-documentation');
 var concat = require('gulp-concat');
 var header = require('gulp-header');
 var footer = require('gulp-footer');
@@ -219,10 +219,9 @@ gulp.task('clean-docs', function () {
 
 gulp.task('docs', ['clean-docs'], function () {
   return gulp.src('src/prebid.js')
-    .pipe(concat('readme.md'))
-    .pipe(gulpJsdoc2md())
+    .pipe(gulpDocumentation('md'))
     .on('error', function (err) {
-      gutil.log('jsdoc2md failed:', err.message);
+      gutil.log('`gulp-documentation` failed:', err.message);
     })
     .pipe(gulp.dest('docs'));
 });

package.json

@@ -33,6 +33,7 @@
     "chai": "^3.3.0",
     "coveralls": "^2.11.11",
     "del": "^2.2.0",
+    "documentation": "^5.2.2",
     "ejs": "^2.5.1",
     "es5-shim": "^4.5.2",
     "eslint-config-standard": "^10.2.1",
@@ -51,7 +52,7 @@
     "gulp-footer": "^1.0.5",
     "gulp-header": "^1.7.1",
     "gulp-if": "^2.0.2",
-    "gulp-jsdoc-to-markdown": "^1.2.1",
+    "gulp-documentation": "^3.2.1",
     "gulp-optimize-js": "^1.1.0",
     "gulp-rename": "^1.2.0",
     "gulp-replace": "^0.4.0",