[Request Tracing] Data format does not have `End timestamp`

[PierreZ]

I was writing a parser for the tracing when I realized that the documentation about the data format is wrong:

Documentation: https://github.com/apple/foundationdb/blob/0a0b4cf3332ebf1002ca9bdf121fd95167c0607f/documentation/sphinx/source/request-tracing.rst#L66

Implementation: https://github.com/apple/foundationdb/blob/0a0b4cf3332ebf1002ca9bdf121fd95167c0607f/flow/Tracing.actor.cpp#L166

Example of parsed tracings events on release-7.0:

[src/parser.rs:165] self = FDBTrace {
    source: "127.0.0.1:4500",
    trace_id: 559608619813946798,
    span_id: 10019690504431922428,
    start_timestamp: 1629382225.5641315,
    duration: 1.00061202s,
    operation_name: "NAPI:readVersionBatcher",
    tags: {},
    parent_span_ids: [
        16391314303740626100,
    ],
}

[PierreZ]

Can be closed, PR on master and release-7.0 has been merged. Thanks!