[mkdocs] Add project-level documentation #17537

Job	Run time
test_suite_tag	0s
check_md_wf_files	0s
test_suite_master / Determine best available runner	1s
get_run_id	0s
test_suite_pr	0s
test_suite_master / Smoke tests (ext4, true)	22m 23s
test_suite_master / LPS LOC test suite	22m 22s
test_suite_master / Networking test suite	22m 14s
test_suite_master / EVE upgrade test suite (ext4)	22m 3s
test_suite_master / Smoke tests (ext4, false)	22m 15s
test_suite_master / EVE upgrade test suite (zfs)	22m 11s
test_suite_master / Smoke tests (zfs, true)	22m 19s
test_suite_master / Smoke tests (zfs, false)	21m 56s
test_suite_master / Storage test suite (ext4)	22m 48s
test_suite_master / Storage test suite (zfs)	22m 16s
test_suite_master / User apps test suite	22m 28s
test_suite_master / Virtualization test suite	33m 22s
	4h 38m 38s

Provide feedback