beginShape() documentation lack LINE_STRIP shape mode

Issue description

Examples shown encourage users who wants to draw multiple consecutive line segments to use "With no mode specified, the shape can be any irregular polygon".

But the default POLYGON mode doesn't work if user supply only 2 vertices...

The example code is working with four vertices, but doesn't work anymore if you comment two of them !

URL(s) of affected page(s)

https://processing.org/reference/beginShape_.html

Proposed fix

The fourth example should use beginShape(LINE_STRIP) and LINE_STRIP should be mentionned in mode's list.

noFill();
beginShape(LINE_STRIP);
vertex(30, 20);
vertex(85, 20);
endShape();

https://processing.org/reference/beginShape_.html の対象となる beginShape() リファレンスページから始め、4番目の例とシェイプモードの一覧を確認します。例を LINE_STRIP を使用するように更新し、そのモードを一覧に追加してから、レンダリングされたドキュメントと2頂点の例を検証します。