Merge pull request #8 from mnm678/flexible-data-format

Remove strict json requirement from metadata description

Author: lukpueh

content/metadata.md

@@ -15,7 +15,8 @@ The signed metadata files always include an expiration date. This ensures
 that outdated metadata will be detected and that
 clients can refuse to accept metadata older than that which they've already seen.
 
-All TUF metadata uses a subset of the JSON object format. When calculating the
+Implementers of TUF may use any data format for metadata files. The examples
+here use a subset of the JSON object format. When calculating the
 digest of an object, we use the [Canonical JSON](http://wiki.laptop.org/go/Canonical_JSON) format. Implementation-level detail about the metadata can be found in the [spec](https://github.com/theupdateframework/specification/blob/master/tuf-spec.md).
 
 There are four required top-level roles, each with their own metadata file.