Remove prism's package-lock.json from git

It's generated automatically.  Also add to .gitignore

[ci skip]

Author: d-torrance

M2/Macaulay2/editors/.gitignore

@@ -5,6 +5,7 @@ highlightjs/macaulay2.js
 Macaulay2Web/M2-symbols.ts
 prism/macaulay2.js
 prism/node_modules/
+prism/package-lock.json
 prism/prism.js
 prism/prism.js.LICENSE.txt
 pygments/macaulay2.py