KHR_draco_mesh_compression: Clarify accessor details and indices resolving.

Please clarify, which values the accessor should have:

count: Is this the value for resolved or unresolved values? From my understanding it should be the resolved value.

componentType: If the uncompressed data is decoded, the result has the given component type and no conversion is needed? I assume no conversion is needed.

type: If the uncompressed data is decoded, the number of elements are "correct" and no conversion is needed? Like above, I assume no conversion is needed.

Finally, it should be explained, how indices have to be resolved.

Review the KHR_draco_mesh_compression specification and its accessor and index-resolution guidance. Clarify whether count, componentType, and type describe resolved data, and document how indices are resolved; the issue is complete when these cases are explicit.

Written by the indexing model from the issue text.