Remove MIT License, move License.txt to root and update build script (#1452)

Author: SteveL-MSFT

LICENSE

@@ -143,8 +143,8 @@ Synopsis: Copy all of the files that belong in the module to one place in the la
 #>
 task LayoutModule BuildMainModule, BuildMamlHelp, {
     $extraFiles =
+        'License.txt',
         'PSReadLine/Changes.txt',
-        'PSReadLine/License.txt',
         'PSReadLine/SamplePSReadLineProfile.ps1',
         'PSReadLine/PSReadLine.format.ps1xml',
         'PSReadLine/PSReadLine.psm1'

PSReadLine/License.txt renamed to License.txt

@@ -25,7 +25,6 @@
     <None Include="PSReadLine.format.ps1xml" CopyToOutputDirectory="PreserveNewest" />
     <None Include="SamplePSReadLineProfile.ps1" />
     <None Include="Changes.txt" />
-    <None Include="License.txt" />
   </ItemGroup>
   <ItemGroup>
     <None Include="..\docs\about_PSReadLine.help.txt" Link="docs\about_PSReadLine.help.txt" />

PSReadLine.build.ps1

@@ -240,7 +240,7 @@ The change log is available [here](https://github.com/PowerShell/PSReadLine/blob
 
 PSReadLine is licensed under the [2-Clause BSD License][].
 
-[2-Clause BSD License]: https://github.com/PowerShell/PSReadLine/blob/master/PSReadLine/License.txt
+[2-Clause BSD License]: https://github.com/PowerShell/PSReadLine/blob/master/License.txt
 
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