Add '.cmd' to yarn and npm commands for windows


#1

Not sure if this should be done here or on git, but because this is such a small bug I considered it informal as the bug reporting suggests.

Issue details

Small quality of life issue with install: running the demo on windows and had to add yarn.cmd and npm.cmd on lines 141 and 149 of bin/pm.js.

error without yarn.cmd Error: spawnSync yarn ENOENT at _errnoException (util.js:992:11) at spawnSync (child_process.js:579:20) at Object.execFileSync (child_process.js:616:13) at run (C:\Users\tisquantum\prosemirror\bin\pm.js:80:16) at install (C:\Users\tisquantum\prosemirror\bin\pm.js:141:3) at start (C:\Users\tisquantum\prosemirror\bin\pm.js:40:9) at Object.<anonymous> (C:\Users\tisquantum\prosemirror\bin\pm.js:365:1) at Module._compile (module.js:652:30) at Object.Module._extensions..js (module.js:663:10) at Module.load (module.js:565:32)

error without npm.cmd Error: spawnSync npm ENOENT at _errnoException (util.js:992:11) at spawnSync (child_process.js:579:20) at Object.execFileSync (child_process.js:616:13) at run (C:\Users\tisquantum\prosemirror\bin\pm.js:80:16) at mods.forEach.repo (C:\Users\tisquantum\prosemirror\bin\pm.js:149:5) at Array.forEach (<anonymous>) at build (C:\Users\tisquantum\prosemirror\bin\pm.js:147:8) at install (C:\Users\tisquantum\prosemirror\bin\pm.js:143:3) at start (C:\Users\tisquantum\prosemirror\bin\pm.js:40:9) at Object.<anonymous> (C:\Users\tisquantum\prosemirror\bin\pm.js:365:1)

Steps to reproduce

run bin/pm install on windows 10 version 1803