Add plugin types (#1527)

Covered following plugins
- addAttributesToSVGElement.js 
- addClassesToSVGElement.js 
- cleanupAttrs.js 
- convertEllipseToCircle.js 
- removeAttributesBySelector.js 
- removeAttrs.js 
- removeComments.js 
- removeDesc.js 
- removeDoctype.js 
- removeElementsByAttr.js 
- removeEmptyText.js 
- removeMetadata.js 
- removeRasterImages.js 
- removeScriptElement.js 
- removeStyleElement.js 
- removeTitle.js 
- removeXMLProcInst.js

plugins/removeScriptElement.js

@@ -12,8 +12,9 @@ exports.description = 'removes <script> elements (disabled by default)';
  *
  * https://www.w3.org/TR/SVG11/script.html
  *
- *
  * @author Patrick Klingemann
+ *
+ * @type {import('../lib/types').Plugin<void>}
  */
 exports.fn = () => {
   return {