DDSWEB — Correct minor inconsistencies in naming

The XSD uses the element name "domain_participant" while the REST resources refer to it as "participant". The two should be aligned.

In some places of the document it refers to the different content types as webdds+xml and wendds+json. Other parts of the document use dde-web+xml and dds-web+json for essentially the same. These should be aligned.

Correct the naming inconsistencies

Use "domain_participant" for the resource URIs instead of "participant"

Use "dds-web+xml" instead of "webdds+xml"

This resolution shall apply after all other issue resolutions have been applied.