ready v0.6.1 release

Add SSZ examples (#128)

* Add ssz examples

* Use plural for signed validator registrations

* Make register validator example fork independent

specs release for electra

V0.4.0 (#97)

* formatting

* add openapi entry for v0.4.0

V0.3.0 (#70)

* formatting

* mint `v0.3.0`

fix builder spec link, add honest validator spec

release v0.1.0

update spec to v0.0.0