javapackager: a number of documentation corrections and enhancements

FULL PRODUCT VERSION :
java version "9.0.1"
Java(TM) SE Runtime Environment (build 9.0.1+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.1+11, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Not OS specific, applies to all OSes, or all OSes combined in one issue

A DESCRIPTION OF THE PROBLEM :
Docs and example required:

- additional documentation and examples around how to add a license when building a package would be helpful. After a bit of searching on google and experimenting with couple of combinations of CLI options I was able to figure it out. For e.g. using the -srcfiles and -srcfolder flags multiple times does make the build progress but the package built either is corrupt or does not build

- just adding mac.signing-key-developer-id-app=xxxxx isn't enough, needs the other code-sign related flags as well, possibly key should be in the Mac KeyStore when building it (check if id provided is the correct one, additional examples would definitely help to reduce or eliminate experimentation and assumptions)

- code signing examples for Windows and MacOSX will certainly help quite a bit

- .deb packages take a long time to build, some additional flags that can help. Some findings along the lines on how to speed up dpkg-build:
export CCACHE_DIR=/home/$USER/.ccache

export CCACHE_HASHDIR=$CCACHE_DIR

export DEB_BUILD_OPTIONS="${DEB_BUILD_OPTIONS} --preserve-envvar=CCACHE_DIR --prepend-path=/usr/lib/ccache parallel=jobs"

echo "Debian build options: ${DEB_BUILD_OPTIONS}"

Do you have something in the lines of the above to help speed up the dpkg-build execution process.

Docs correction:
- jvmUserArg is referred to in the documentation with examples, while in the usage documentation jvmOptions is used (discrepancy between the names of flags), see https://docs.oracle.com/javase/8/docs/technotes/tools/unix/javapackager.html and https://docs.oracle.com/javase/9/deploy/self-contained-application-packaging.htm#JSDPG585

- same goes for mac.signing-key-user-name while there is no mention of it in the javapackager usage documentation, it takes the full name of the user i.e. Jane Doe

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Corrected documentations, additional documentations and examples
ACTUAL -
Incorrect documentations, lack of documentation and examples

REPRODUCIBILITY :
This bug can be reproduced always.