Provide info on job params in YAML about bootique-job

[atomashpolskiy]

In fact, for SingleJob the best way would be to replace

public JobMetadata getMetadata() {
    return delegate.getMetadata();
}

with

public JobMetadata getMetadata() {
    return merge(execution.getParams(), delegate.getMetadata());
}

[andrus]

This seems to muddle the distinction between job singleton parameters and parameters of a given job run. Whether this is important or not, I have no idea yet.

[andrus]

After discussing offline, it actually makes sense, as "execution" is simply a param set.

[andrus]

While this issue is still something that we will need to address, it begs a bigger question on the distinction between a job and an execution, and will probably result in refactoring Job API (e.g. base metadata can be gathered from annotations, while execution metadata may be passed to the "run" method). So closing this task, as we won't be implementing it as described.