Add developer docs

Comments addressed by
12955: Update developer docs | https://gerrit.o-ran-sc.org/r/c/smo/teiv/+/12955

Issue-ID: SMO-150
Change-Id: Id13c3485f0c074226e2bf2172cc30aec30b03f02
Signed-off-by: JvD_Ericsson <jeff.van.dam@est.tech>
34 files changed