Clarification on license & distribution rights

Signed-off-by: Dries007 <admin@dries007.net>

README.md

@@ -7,4 +7,53 @@ Target comparability is Java 8, Minecraft 1.7.10+ (Missing versions may be reque
 
 For Forge there will be separate versions with MC version included in the jar's name as appendix.
 
-Copyright © 2017 - 2018 Dries007. All rights reserved
+License / Distribution
+----------------------
+
+Copyright © 2017 - 2018 Dries007. **All rights reserved.**
+
+[Publicly visible source != open source!](https://choosealicense.com/no-permission/)
+
+### Source code permissions:
+
+- If you want to use my API and have received permission to do so, in accordance with the [The MCLink website](https://mclink.dries007.net/)'s rules,
+  you are also allowed to use the API's source code, as long as you do not remove the copyright information.
+  Attribution is not required, but appreciated.
+- If you find any small snippets of code useful, please attribute. (A source code comment is good enough.)
+  A small snippet is defined as a piece of code that helps you solve a problem in your own project, 
+  but not lead to a duplication of features of MCLink.
+- You are allowed to fork and edit this repository.
+- You are allowed to create pull requests to contribute to the project, if you have the right to agree to the following statement:
+- By contributing you grant to the MCLink’s maintainers, contributors, users and to Dries007 a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable license to reproduce, create derivative works of, publicly display, publicly perform, sublicense, and distribute your contributions and such derivative works.
+
+###  Distribution rules, highest priority first:
+
+1. You are not allowed to distribute _or use_ modified versions.
+   This includes stripping signing information!
+2. Official builds can be distributed on any freely accessible platform.
+   1. List of official build sources:
+      1. [The MCLink website](https://mclink.dries007.net/)
+      2. CurseForge [1](https://www.curseforge.com/minecraft/mc-mods/mclink) or [2](https://minecraft.curseforge.com/projects/mclink)
+      3. [The build server](https://jenkins.dries007.net/job/MCLink/)
+   2. You are allowed to _privately_ use a modified version while developing a Pull Request.
+   3. A freely accessible platform is defined as a platform requiring no payment for access.
+      So called "Premium" access (for example payment in exchange for removal of advertisements or faster downloads) is allowed.
+   4. So called "Private modpacks" are allowed, provided they are not against rule 3. 
+3. You cannot explicitly upload any build to any platform for monetary gain (such as using Adfly links, reward points, etc).
+    1. CurseForge modpacks are allowed to enable Curse reward points, if they use the official build from CurseForge, and abide by the CurseForge Terms of Service.
+5. Mod archives are allowed to archive official builds of the mod privately.
+   If the official sources no longer offer a version or they inaccessible for 1 month, the builds may be publicly distributed.
+
+Exceptions may be granted by written permission.
+Such permission can be requested via any of the contact options listed on [the about page of the MCLink website](https://mclink.dries007.net/about).
+
+If you come across a build you suspect does not adhere to these rules, please inform me. Thanks!
+
+<!--
+For the curious: A little background info on these rules:
+
+- I don't want to get issue reports about builds I did not make.
+- This mod uses my own backend service.
+- I spend a lot of time and effort making this.
+- The money I get from CurseForge's reward points helps pay for the server MCLink runs on.
+-->