[Server] Change insert() to upsert in page "Modify Chunk Size in a Sharded Cluster"

Hi team,

In the page Modify Chunk Size in a Sharded Cluster, the command to modify the maximum chunk size is:

db.settings.insertOne( { _id:"chunksize", value: <sizeInMB> } )

However, if the maximum chunk size has already been modified, this returns a "duplicate key error".

Instead, this command should be an upsert so it's repeatable:

db.settings.updateOne( { _id:"chunksize" }, { $set: { _id:"chunksize", value: <sizeInMB> } }, { upsert: true } )

Thanks,
Matt