Changelog:
===========
- replaces the unicode micro symbol with greek letter mu,
visually identical but should fix nfkc normalisations issues.
- introduces "intersphinx_registry" as a new dependency
which is recommended only to build documentation.
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
