Docs: Update recipes to install gulp@next

Author: phated

docs/getting-started.md

@@ -27,7 +27,7 @@ If you don't have a package.json, create one. If you need help, run an `npm init
 Run this command in your project directory:
 
 ```sh
-npm install --save-dev gulp
+npm install --save-dev gulp@next
 ```
 
 #### Create a `gulpfile`

docs/recipes/delete-files-folder.md

@@ -6,7 +6,7 @@ You might want to delete some files before running your build. Since deleting fi
 Let's use the [`del`](https://github.com/sindresorhus/del) module for this example as it supports multiple files and [globbing](https://github.com/sindresorhus/multimatch#globbing-patterns):
 
 ```sh
-$ npm install --save-dev gulp del
+$ npm install --save-dev gulp@next del
 ```
 
 Imagine the following file structure:
@@ -50,7 +50,7 @@ You might want to delete some files after processing them in a pipeline.
 We'll use [vinyl-paths](https://github.com/sindresorhus/vinyl-paths) to easily get the file path of files in the stream and pass it to the `del` method.
 
 ```sh
-$ npm install --save-dev gulp del vinyl-paths
+$ npm install --save-dev gulp@next del vinyl-paths
 ```
 
 Imagine the following file structure:

docs/recipes/mocha-test-runner-with-gulp.md

@@ -3,7 +3,7 @@
 ### Passing shared module in all tests
 
 ```js
-// npm install gulp gulp-mocha
+// npm install gulp@next gulp-mocha
 
 var gulp = require('gulp');
 var mocha = require('gulp-mocha');
@@ -22,7 +22,7 @@ gulp.task('default', function() {
 ### Running mocha tests when files change
 
 ```js
-// npm install gulp gulp-mocha gulplog
+// npm install gulp@next gulp-mocha gulplog
 
 var gulp = require('gulp');
 var mocha = require('gulp-mocha');

docs/recipes/only-pass-through-changed-files.md

@@ -4,7 +4,7 @@ Files are passed through the whole pipe chain on every run by default. By using
 
 
 ```js
-// npm install --save-dev gulp gulp-changed gulp-jscs gulp-uglify
+// npm install --save-dev gulp@next gulp-changed gulp-jscs gulp-uglify
 
 var gulp = require('gulp');
 var changed = require('gulp-changed');

docs/recipes/pass-arguments-from-cli.md

@@ -1,7 +1,7 @@
 # Pass arguments from the command line
 
 ```js
-// npm install --save-dev gulp gulp-if gulp-uglify minimist
+// npm install --save-dev gulp@next gulp-if gulp-uglify minimist
 
 var gulp = require('gulp');
 var gulpif = require('gulp-if');

docs/recipes/rollup-with-rollup-stream.md

@@ -4,7 +4,7 @@ Like Browserify, [Rollup](https://rollupjs.org/) is a bundler and thus only fits
 
 ## Basic usage
 ```js
-// npm install --save-dev rollup-stream vinyl-source-stream
+// npm install --save-dev gulp@next rollup-stream vinyl-source-stream
 var gulp = require('gulp');
 var rollup = require('rollup-stream');
 var source = require('vinyl-source-stream');
@@ -24,7 +24,7 @@ gulp.task('rollup', function() {
 
 ## Usage with sourcemaps
 ```js
-// npm install --save-dev rollup-stream gulp-sourcemaps vinyl-source-stream vinyl-buffer
+// npm install --save-dev gulp@next rollup-stream gulp-sourcemaps vinyl-source-stream vinyl-buffer
 // optional: npm install --save-dev gulp-rename
 var gulp = require('gulp');
 var rollup = require('rollup-stream');

docs/recipes/run-grunt-tasks-from-gulp.md

@@ -7,7 +7,7 @@ It is possible to run Grunt tasks / Grunt plugins from within Gulp. This can be
 very simple example `gulpfile.js`:
 
 ```js
-// npm install gulp grunt grunt-contrib-copy --save-dev
+// npm install gulp@next grunt grunt-contrib-copy --save-dev
 
 var gulp = require('gulp');
 var grunt = require('grunt');

docs/recipes/server-with-livereload-and-css-injection.md

@@ -2,10 +2,10 @@
 
 With [BrowserSync](https://browsersync.io) and gulp, you can easily create a development server that is accessible to any device on the same WiFi network. BrowserSync also has live-reload built in, so there's nothing else to configure.
 
-First install the module:
+First install the modules:
 
 ```sh
-$ npm install --save-dev browser-sync
+$ npm install --save-dev gulp@next browser-sync
 ```
 
 Then, considering the following file structure...

docs/recipes/split-tasks-across-multiple-files.md

@@ -17,7 +17,7 @@ tasks/
 Install the `gulp-hub` module:
 
 ```sh
-npm install --save-dev gulp-hub
+npm install --save-dev gulp@next gulp-hub
 ```
 
 Add the following lines to your `gulpfile.js` file:

docs/recipes/using-external-config-file.md

@@ -30,7 +30,7 @@ Beneficial because it's keeping tasks DRY and config.json can be used by another
 ###### `gulpfile.js`
 
 ```js
-// npm install --save-dev gulp gulp-uglify merge-stream
+// npm install --save-dev gulp@next gulp-uglify merge-stream
 var gulp = require('gulp');
 var uglify = require('gulp-uglify');
 var merge = require('merge-stream');

docs/recipes/using-multiple-sources-in-one-task.md

@@ -1,7 +1,7 @@
 # Using multiple sources in one task
 
 ```js
-// npm install --save-dev gulp merge-stream
+// npm install --save-dev gulp@next merge-stream
 
 var gulp = require('gulp');
 var merge = require('merge-stream');
@@ -20,7 +20,7 @@ gulp.task('test', function() {
 `gulp.src` will emit files in the order they were added:
 
 ```js
-// npm install gulp gulp-concat
+// npm install gulp@next gulp-concat
 
 var gulp = require('gulp');
 var concat = require('gulp-concat');