show when additional properties are allowed, fixes #19

examples/docs/abstract.schema.md

examples/docs/arrays.schema.md

examples/docs/complex.schema.md

examples/docs/constants.schema.md

examples/docs/custom.schema.md

examples/docs/deepextending.schema.md

examples/docs/definitions.schema.md

examples/docs/enums.schema.md

examples/docs/example.schema.md

examples/docs/examples.schema.md

examples/docs/extending.schema.md

examples/docs/extensible.schema.md

examples/docs/simple.schema.md

examples/docs/simpletypes.schema.md

examples/docs/subdir/subdir.schema.md

examples/generated-schemas/complex.schema.json

examples/schemas/complex.schema.json

lib/markdownWriter.js

templates/md/header.ejs

templates/md/properties.ejs