Remove invalid unit from documentation and add valid units pc, em and ex (#3189)

Fixes #3188

Co-authored-by: Dominik Kuhnke <d.kuhnke@metis-ag.com>
Co-authored-by: Lukas Holländer <lukas.hollaender@yworks.com>

Author: 3 people

src/jspdf.js

@@ -178,7 +178,7 @@ function TilingPattern(boundingBox, xStep, yStep, gState, matrix) {
  * @param {Object} [options] - Collection of settings initializing the jsPDF-instance
  * @param {string} [options.orientation=portrait] - Orientation of the first page. Possible values are "portrait" or "landscape" (or shortcuts "p" or "l").<br />
  * @param {string} [options.unit=mm] Measurement unit (base unit) to be used when coordinates are specified.<br />
- * Possible values are "pt" (points), "mm", "cm", "m", "in" or "px". Note that in order to get the correct scaling for "px"
+ * Possible values are "pt" (points), "mm", "cm", "in", "px", "pc", "em" or "ex". Note that in order to get the correct scaling for "px"
  * units, you need to enable the hotfix "px_scaling" by setting options.hotfixes = ["px_scaling"].
  * @param {string/Array} [options.format=a4] The format of the first page. Can be:<ul><li>a0 - a10</li><li>b0 - b10</li><li>c0 - c10</li><li>dl</li><li>letter</li><li>government-letter</li><li>legal</li><li>junior-legal</li><li>ledger</li><li>tabloid</li><li>credit-card</li></ul><br />
  * Default is "a4". If you want to use your own format just pass instead of one of the above predefined formats the size as an number-array, e.g. [595.28, 841.89]