Moved the release notes under docs

Looks nice there, linking to it from the release
announcement.

apply patch from O. Hartmann: fix build on FreeBSD CURRENT

Update PoCL version to 5.0

CMake: rename variable

Update PoCL version to 4.0

Bump sover for 3.1 and drop -pre version suffix for release

3.1 release preparations

Merge branch 'macos' of github.com:isuruf/pocl into release_3_0

Replace LLVMGetCalledFunctionType() with getFunctionType() to fix cas…

…ting related crash with LLVM 14

Add mention of problems with ICD on Mac OS X