Add License to share on github

LICENSE.txt

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+LaTeX4EI Template                                               Date: 2016-01-06
+
+
+
+LICENSE:
+
+You are allowed to create and share documents created
+with this template under the following conditions:
+
+
+* visible reference to www.latex4ei.de:
+    you have to place a "based on template from www.latex4ei.de" or similar in your documents.
+
+
+* no commercial use:
+    you are not allowed to sell any part of this template or documents created with this template.
+
+
+* limited modification:
+    you are allowed to modify the template for personal use.
+    you are NOT allowed to distribute modified versions of this template on your own.
+    Please push back your modifications to us so that we have the chance to integrate it.
+
+
+If you want to publish your latex code you are allowed to publish the source code
+of this template as well but you have to make sure that a copy of this license is included.
+
+
+© 2011-2019, LaTeX4EI