Update file transfer how-to

[FyzHsn]

Fix the list of typos / grammatical errors:

• [ ] "We can perform file transfer operations pre or post electron execution here we illustrate how to perform file transfer using Rsync locally and remotely via SSH."
• [ ] "We first define a source & destination filepath where we want to transfer a file from the source_filepath location to the destination_filepath location as well as create an empty file in source_filepath to have a file to transfer." (Run on sentence?)
• [ ] "# Dispatch a workflow to transfer from source to destination, and write to destination file". (Comma should be removed)
• [ ] "# read from destination file which we wrote tochange to# Read contents of destination file."
• [ ] "After executing the workflow we now see a copy of the file (source_filepath) located in my_dest_file. This file transfer occured prior to electon execution." (The flow is awkward + missing comma in the first sentence)
• [ ] "After workflow execution the file located at source_filepath will be transfered to host 44.202.86.215 in the host’s filesystem (/home/ubuntu/my_dest_file). This file transfer occurs after electron execution." (Same issues as above)
• [ ] "Similarly we can perform file transfers using Rsync via SSH in order to transfer a file located in source_filepath to a remote host’s filesystem located at /home/ubuntu/my_dest_file" (Missing period at the end of this sentence)
• [ ] "We can perform file transfer between an S3 bucket and local filesystem using the boto3 library. Here we show a simple example where a zip file is downloaded from the S3 bucket before its execution. The electron performs necessary operations on them and the processed files are uploaded back to the S3 bucket." ->

"We can transfer files between a S3 bucket and the local filesystem using the boto3 library. Below, we show an example where:

1. A zip file is downloaded from a S3 bucket before the electron execution.
2. The electron is executed and processed files are uploaded back to the S3 bucket."

• [ ] Reference the file transfer section in the concepts page in the How-to guide.