[DOCS] Add documentation for pc.path (#1809)
[DOCS] Add documentation for pc.path (#1809)

* add jsdocs for getExtension

* add jsdocs for isRelativePath

* add jsdocs for extractPath

MicroWorldwide/PlayCanvas,sereepap2029/playcanvas,MicroWorldwide/PlayCanvas,aidinabedi/playcanvas-engine,sereepap2029/playcanvas,aidinabedi/playcanvas-engine,sereepap2029/playcanvas,playcanvas/engine,playcanvas/engine