title: Please update your includePath
body: <p>I'm in a school course that uses C++. With the code they give us, we have stuff in the headers like: </p>
  
  <pre><code>#include &lt;cstdlib&gt;
  #include &lt;cmath&gt;
  #include &lt;iostream&gt;
  #include "cs221util/PNG.h"
  #include "cs221util/HSLAPixel.h"
  </code></pre>
  
  <p>I get the errors </p>
  
  <pre><code>{
      "resource": "/home/k/xxx/cs221/lab_debug/sketchify.cpp",
      "owner": "C/C++",
      "code": "1696",
      "severity": 8,
      "message": "#include errors detected. Please update your includePath. Squiggles are disabled for this translation unit (/home/k/xxx/cs221/lab_debug/sketchify.cpp).",
      "source": "C/C++",
      "startLineNumber": 4,
      "startColumn": 1,
      "endLineNumber": 4,
      "endColumn": 27
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>{
      "resource": "/home/k/xxx/cs221/lab_debug/sketchify.cpp",
      "owner": "C/C++",
      "code": "1696",
      "severity": 8,
      "message": "cannot open source file \"iostream\"",
      "source": "C/C++",
      "startLineNumber": 3,
      "startColumn": 1,
      "endLineNumber": 3,
      "endColumn": 20
  }
  </code></pre>
  
  <p>even though all everything compiles and runs fine. I was looking online and perhaps a solution is modifying c_cpp_properties.json? I opened that and have no idea what anything in that file means. What am I supposed to do? What does everything mean?</p>