Add 'RPC failed' error handling while fetching from gitee.com

Added information which describes how to change http and https postBuffer, which solves fetching from gitee.com problems which may occur during the build.

Closes https://gitlab.eclipse.org/eclipse/oniro-core/meta-openharmony/-/issues/36

Signed-off-by: Grzegorz Gwóźdź grzegorz.gwozdz@huawei.com