Add quick intro to embedded graphs to README.
Add quick intro to embedded graphs to README.

Code4SA/censusreporter,4bic/censusreporter,sseguku/simplecensusug,sseguku/simplecensusug,4bic/censusreporter,sseguku/simplecensusug,Code4SA/censusreporter,Code4SA/censusreporter,4bic/censusreporter,Code4SA/censusreporter