Release v2.2.1

Hi everyone,

with VOLK 2.2.0, we introduced another AVX rotator bug which is fixed with this release.
In the process 2 more bugs were identified and fixed. Further, we saw some documentation improvements.

Contributors

• Clayton Smith [email protected]
• Michael Dickens [email protected]

Changes

• Fix loop bound in AVX rotator
• Fix out-of-bounds read in AVX2 square dist kernel
• Fix length checks in AVX2 index max kernels
• includes: rearrange attributes to simplify macros Whitespace
• kernels: fix usage in header comments