create v1.1 catalog.json
create v1.1 single_entry.json
Create catalog-sample-extended.csv
Create catalog-sample-extended.json
Create catalog-sample.csv
Create catalog-sample.json
Create catalog-template-extended.csv
Create catalog-template-extended.json
Create catalog-template.csv
Create catalog-template.json
updating accessLevelComment to rights
adding expanded guidance for systemOfRecords
Create metadata-resources.md
Create iso8601_guidance.md
Update schema.md

Seeking to address https://github.com/project-open-data/project-open-data.github.io/issues/292.  

Note that this is accompanied by an appendix that is [still under construction](https://github.com/project-open-data/project-open-data.github.io/blob/metadata-v-1.1/iso8601_guidance.md#accrualperiodicity).
new extended guidance for `publisher`

Following through on with https://github.com/project-open-data/project-open-data.github.io/issues/296.
adding language for `isPartOf`
accessURL, downloadURL, webService

* refined accessURL
* added downloadURL
* removed webService

addressing #335, #291
update format and add mediatype
use markdown syntax for named anchor/id and links