Add new shapes enabled by LockupLinear

[PaulRBerg]

Task

As originally suggested by @andreivladbrg here, we should document the new shapes enabled by LockupLinear (part of Lockup v2.0.0):

Note for self: we need to come up with bespoke names for these shapes.

Scenario 5

Toggle to see the code:

<FunctionPlot
  options={{
    data: [
      { fn: "0", range: [0, 25], color: "#f77423" },
      { fn: "(4/3) * (x - 25)", range: [25, 100], color: "#f77423" },
      {
        points: [
          [0, 0],
          [25, 0],
        ],
        fnType: "points",
        graphType: "polyline",
        color: "#f77423",
      },
    ],
  }}
/>

Scenario 6

Toggle to see the code:

<FunctionPlot
  options={{
    data: [
      { fn: "25", range: [0, 50], color: "#f77423" }, // Constant at y=25 from x=0 to x=50
      { fn: "1.5 * (x - 50) + 25", range: [50, 100], color: "#f77423" }, // Linear rise with slope 1.5 starting from y=25 at x=50
      {
        points: [
          [0, 25],
          [50, 25],
        ],
        fnType: "points",
        graphType: "polyline",
        color: "#f77423",
      },
    ],
  }}
/>