[FLINK-7434][doc] scafolding with "sbt new"

Since the generated project is an sbt project, it is
much more straightfoward for the user to create it with
the new "sbt new" command than by using giter8 (which
requires to install giter8 just for that purpose).

This closes apache#4531.

docs/quickstart/scala_api_quickstart.md

@@ -41,25 +41,20 @@ These templates help you to set up the project structure and to create the initi
 
 ### Create Project
 
+You can scafold a new project via either of the following two methods:
+
 <ul class="nav nav-tabs" style="border-bottom: none;">
- <li class="active"><a href="#giter8" data-toggle="tab">Use <strong>Giter8</strong></a></li>
- <li><a href="#clone-repository" data-toggle="tab">Clone <strong>repository</strong></a></li>
+ <li class="active"><a href="#sbt_template" data-toggle="tab">Use the <strong>sbt template</strong></a></li>
  <li><a href="#quickstart-script-sbt" data-toggle="tab">Run the <strong>quickstart script</strong></a></li>
 </ul>
 
 <div class="tab-content">
- <div class="tab-pane active" id="giter8">
- {% highlight bash %}
- $ g8 tillrohrmann/flink-project
- {% endhighlight %}
- This will create a Flink project in the <strong>specified</strong> project directory from the <a href="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/tillrohrmann/flink-project.g8">flink-project template</a>.
- If you haven't installed <a href="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/n8han/giter8">giter8</a>, then please follow this <a href="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/n8han/giter8#installation">installation guide</a>.
- </div>
- <div class="tab-pane" id="clone-repository">
+ <div class="tab-pane active" id="sbt_template">
  {% highlight bash %}
- $ git clone https://github.com/tillrohrmann/flink-project.git
+ $ sbt new tillrohrmann/flink-project.g8
  {% endhighlight %}
- This will create the Flink project in the directory <strong>flink-project</strong>.
+ This will will prompt you for a couple of parameters (project name, flink version...) and then create a Flink project from the <a href="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/tillrohrmann/flink-project.g8">flink-project template</a>.
+ You need sbt >= 0.13.13 to execute this command. You can follow this <a href="https://www.scala-sbt.org/download.html">installation guide</a> to obtain it if necessary.
  </div>
  <div class="tab-pane" id="quickstart-script-sbt">
  {% highlight bash %}