Add Javadoc comments

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

Author: bact

src/main/java/org/spdx/tools/CONTRIBUTING.md

@@ -1,15 +1,18 @@
 Contributing
 ============
+
 Thank you for your interest in `Spdx-Java-Library`. The project is open-source software, and bug reports, suggestions, and most especially patches are welcome.
 
 Issues
 ------
+
 `Spdx-Java-Library` has a [project page on GitHub](https://github.com/spdx/Spdx-Java-Library) where you can [create an issue](https://github.com/spdx/Spdx-Java-Library/issues/new/choose) to report a bug, make a suggestion, or propose a substantial change or improvement that you might like to make. You may also wish to contact the SPDX working group technical team through its mailing list, [spdx-tech@lists.spdx.org](mailto:spdx-tech@lists.spdx.org).
 
 If you would like to work on a fix for any issue, please assign the issue to yourself prior to creating a Pull Request.
 
 Pull Requests
 -------
+
 The source code for `Spdx-Java-Library` is hosted on [github.com/spdx/Spdx-Java-Library](https://github.com/spdx/Spdx-Java-Library). Please review [open pull requests](https://github.com/spdx/Spdx-Java-Library/pulls) and [active branches](https://github.com/spdx/Spdx-Java-Library/branches) before committing time to a substantial revision. Work along similar lines may already be in progress.
 
 To submit a pull request via GitHub, fork the repository, create a topic branch from `master` for your work, and send a pull request when ready. If you would prefer to send a patch or grant access to pull from your own Git repository, please contact the project's contributors by e-mail.
@@ -20,4 +23,5 @@ Once implemented, submit a pull request with `spec/X.X` branch as the parent bra
 
 Licensing
 ---------
-However you choose to contribute, please sign-off in each of your commits that you license your contributions under the terms of [the Developer Certificate of Origin](https://developercertificate.org/). Git has utilities for signing off on commits: `git commit -s` signs a current commit, and `git rebase --signoff <revision-range>` retroactively signs a range of past commits.
+
+However you choose to contribute, please sign-off in each of your commits that you license your contributions under the terms of [the Developer Certificate of Origin](https://developercertificate.org/). Git has utilities for signing off on commits: `git commit -s` signs a current commit, and `git rebase --signoff <revision-range>` retroactively signs a range of past commits.

src/main/java/org/spdx/tools/CompareSpdxDocs.java

@@ -78,6 +78,7 @@ public static void main(String[] args) {
 	}
 
 	/**
+	 * Invoke SPDX document processing functions from the online tool
 	 *
 	 * @param args args[0] is the output Excel file name, all other args are SPDX document file names
 	 * @throws OnlineToolException Exception caught by JPype and displayed to the user