edk2: Remove Contributions.txt and update Readme.md

* Remove the Contributions.txt file from the root of the edk2 repository
  that contained the TianoCore Contribution Agreement.

* Update Readme.md in the root of the edk2 repository to state that
  BSD+Patent is the preferred license for the EDK II project.

https://bugzilla.tianocore.org/show_bug.cgi?id=1373

This change is based on the following emails:

  https://lists.01.org/pipermail/edk2-devel/2019-February/036260.html
  https://lists.01.org/pipermail/edk2-devel/2018-October/030385.html

RFCs with detailed process for the license change:

  https://lists.01.org/pipermail/edk2-devel/2019-March/037669.html
  https://lists.01.org/pipermail/edk2-devel/2019-March/037500.html

Branch for review:

  https://github.com/mdkinney/edk2/tree/Bug_1373_BsdPatentLicense

Cc: Leif Lindholm <[email protected]>
Cc: Andrew Fish <[email protected]>
Cc: Laszlo Ersek <[email protected]>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <[email protected]>

Author: mdkinney

Contributions.txt

@@ -3,17 +3,20 @@
 A modern, feature-rich, cross-platform firmware development environment
 for the UEFI and PI specifications from www.uefi.org.
 
-Contributions to the EDK II open source project are covered by the
-[TianoCore Contribution Agreement 1.1](Contributions.txt)
-
 The majority of the content in the EDK II open source project uses a
-[BSD 2-Clause License](License.txt).  The EDK II open source project contains
-the following components that are covered by additional licenses:
+[BSD-2-Clause Plus Patent License](License.txt).  The EDK II open source project
+contains the following components that are covered by additional licenses:
 * [AppPkg/Applications/Python/Python-2.7.2/Tools/pybench](AppPkg/Applications/Python/Python-2.7.2/Tools/pybench/LICENSE)
 * [AppPkg/Applications/Python/Python-2.7.2](AppPkg/Applications/Python/Python-2.7.2/LICENSE)
 * [AppPkg/Applications/Python/Python-2.7.10](AppPkg/Applications/Python/Python-2.7.10/LICENSE)
 * [BaseTools/Source/C/BrotliCompress](BaseTools/Source/C/BrotliCompress/LICENSE)
 * [MdeModulePkg/Library/BrotliCustomDecompressLib](MdeModulePkg/Library/BrotliCustomDecompressLib/LICENSE)
+* [BaseTools/Source/C/LzmaCompress](BaseTools/Source/C/LzmaCompress/LZMA-SDK-README.txt)
+* [MdeModulePkg/Library/LzmaCustomDecompressLib](MdeModulePkg/Library/LzmaCustomDecompressLib/LZMA-SDK-README.txt)
+* [IntelFrameworkModulePkg/Library/LzmaCustomDecompressLib/Sdk](IntelFrameworkModulePkg/Library/LzmaCustomDecompressLib/LZMA-SDK-README.txt)
+* [BaseTools/Source/C/VfrCompile/Pccts](BaseTools/Source/C/VfrCompile/Pccts/RIGHTS)
+* [EdkCompatibilityPkg/Other/Maintained/Tools/Pccts](EdkCompatibilityPkg/Other/Maintained/Tools/Pccts/README)
+* [MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma](MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/README)
 * [OvmfPkg](OvmfPkg/License.txt)
 * [CryptoPkg/Library/OpensslLib/openssl](CryptoPkg/Library/OpensslLib/openssl/LICENSE)