instruction for Gentoo contains non-existing packages

it suggests to install the necessary dependencies: sudo emerge --ask --update --oneshot $(cat scripts/docs/en/deps/gentoo.md | tr '\n' ' ')
which contains: amphyby@gentux ~/Documents/userver $ cat scripts/docs/en/deps/gentoo.md app-crypt/mit-krb5 dev-cpp/benchmark dev-cpp/gtest dev-cpp/yaml-cpp dev-db/mongodb dev-db/postgresql dev-db/redis dev-lang/python dev-libs/crypto++ dev-libs/hiredis dev-libs/jemalloc dev-libs/libbson dev-libs/libev dev-libs/libfmt dev-libs/mongo-c-driver dev-libs/openssl dev-libs/re2 dev-python/jinja dev-python/pip dev-python/virtualenv dev-python/voluptuous dev-util/ccache dev-util/cmake dev-vcs/git net-dns/c-ares net-libs/grpc net-libs/http-parser net-libs/nghttp2 net-misc/curl net-nds/openldap sys-libs/libbacktrace sys-libs/zlib
and aforementioned command gives: emerge: there are no ebuilds to satisfy "sys-libs/libbacktrace". emerge: searching for similar names... emerge: Maybe you meant any of these: sys-libs/libblockdev, sys-libs/libcap, sys-libs/libaal?

P.S.: using the Release 1.0.0 commit version of Userver*

userver-framework / userver