Adds doc for batch.size

* checking for code/documentation mismatches ... WARNING
Codoc mismatches from documentation object 'importRecords':
importRecords.redcapApiConnection
Code: function(rcon, data, overwriteBehavior = c("normal",
"overwrite"), returnContent = c("count", "ids",
"nothing"), returnData = FALSE, logfile = "", ...,
proj = NULL, batch.size = -1)
Docs: function(rcon, data, overwriteBehavior = c("normal",
"overwrite"), returnContent = c("count", "ids",
"nothing"), returnData = FALSE, logfile = "", ...,
proj = NULL)
Argument names in code not in docs:
batch.size