doc: add license requirements file

Add a documentation file that describes license requirements and
compliance information.

Signed-off-by: Danny Holman <dholman@gymli.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/doc/license-requirements.rst b/doc/license-requirements.rst
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+License requirements
+====================
+
+Note: this manual is *not* intended for legal advice. It is provided to aid
+users navigate license and copyright requirements.
+
+What are licenses?
+------------------
+
+Rune is created and distributed under the `zlib license
+<https://opensource.org/license/zlib>`_. It doesn't have a sole owner, as every
+contributor that submits code or other technical contributions does so under the
+same license and retains ownership of their contribution.
+
+The license is a legal requirement for you (or your company) to use and
+distribute the software. Your application can have a different license, but it
+still needs to comply with the original one.
+
+Requirements
+------------
+
+For the zlib license, as long as you aren't altering any engine source files and
+distributing them, there are no hard license requirements. However, if you do
+decide it is best to modify the engine for your own needs, you would need to
+mark these altered sources as modified from the original and that you made the
+modification(s).
+
+If you use Rune in your application as-is, an acknowledgement in your
+application or documentation is appreciated but not required.
+
+For code that is bundled with or used by Rune itself, there is a section at the
+end of this document that lists requirements for those.
+
+Third-party licenses
+--------------------
+
+Rune itself contains software written by third parties, which is compatible
+with, but not covered by Rune's zlib license. Most, if not all, of these
+dependencies are distributed under permissive open source licenses which require
+attribution by explicitly citing their copyright statement and license text in
+the final product's documentation.
+
+Since the Rune Engine is so large, this can be difficult to do. A good option is
+to include this file in your project's distribution, and you can rename it to
+something suitable to avoid confusion with your own code and assets.