Document the --package/-P and --readme/-R flags

[hegemonic]

In JSDoc 3.3.0, you can use the --package/-P and --readme/-R command-line flags to specify the package and README files. If you omit these flags, JSDoc will look for files named package.json and README.md, respectively, and use those files if it finds them. This behavior is consistent with previous versions. (See jsdoc/jsdoc#708 for more info.)

We need to document this change.

[hegemonic]

I'm also going to use this issue to document the pedantic/lenient/debug/verbose additions and changes for 3.3.0.