[OpenMP] [DOCS] Update OMP5.1 feature status table [NFC]
Adding features in OpenMP 5.1 specification, as documented in feature change history, to the 5.1 table. I alphabetized the rows of the table according to the category. For deprecating master construct, I just used 'other' as the category.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D90802