Add Slack information as a way to contact oneDPL developers. #9218

Job	Run time
documentation	35s
CPU,bknd=dpcpp,cmplr=icpx,ubuntu-20.04,std=с++17,cfg=release	10m 1s
clang-format	12s
FPGA_EMU,bknd=dpcpp,cmplr=icpx,ubuntu-20.04,std=с++17,cfg=release	9m 16s
PSTL offload cpu,bknd=dpcpp,cmplr=icpx,ubuntu-22.04,std=с++17,cfg=release	7m 57s
HOST,bknd=tbb,cmplr=icpx,ubuntu-20.04,std=с++17,cfg=release	12m 9s
codespell	13s
HOST,bknd=omp,cmplr=icpx,ubuntu-20.04,std=с++17,cfg=release	9m 40s
HOST,bknd=omp,cmplr=icpc,macos-11,std=c++17,cfg=release	22m 5s
HOST,bknd=omp,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	6m 27s
HOST,bknd=tbb,cmplr=icx-cl,windows-2019,std=c++17,cfg=release	16m 32s
HOST,bknd=tbb,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	9m 52s
HOST,bknd=tbb,cmplr=cl,windows-2019,std=c++17,cfg=release	16m 42s
HOST,bknd=tbb,cmplr=g++,ubuntu-20.04,std=с++17,cfg=release	10m 38s
CPU,bknd=dpcpp,cmplr=icx,windows-2019,std=c++17,cfg=release	14m 10s
HOST,bknd=tbb,cmplr=clang++,ubuntu-20.04,std=с++17,cfg=release	11m 13s
HOST,bknd=omp,cmplr=clang++,ubuntu-20.04,std=с++17,cfg=release	8m 10s
HOST,bknd=tbb,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	11m 44s
HOST,bknd=tbb,cmplr=icpx,ubuntu-20.04,std=с++17,cfg=release	12m 56s
HOST,bknd=serial,cmplr=g++,ubuntu-20.04,std=с++17,cfg=release	5m 21s
	3h 15m 53s

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