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##### SUMMARY
<!--- Explain the problem briefly below, add suggestions to wording or structure -->
The [PSRP documentation](https://docs.ansible.com/ansible/latest/plugins/connection/psrp.html) mentions `ansible_psrp_connection_backoff` but this seems to be incorrect. The code appears to refer to `ansible_psrp_reconnection_backoff` instead (`reconnection` vs `connection`).
<!--- HINT: Did you know the documentation has an "Edit on GitHub" link on every page ? -->

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
<!--- Write the short name of the rst file, module, plugin, task or feature below, use your best guess if unsure -->
PSRP
lib/ansible/plugins/connection/psrp.py

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/dist-packages/ansible-2.8.0.dev0-py2.7.egg/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.15rc1 (default, Nov 12 2018, 14:31:15) [GCC 7.3.0]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
None
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. OS version, browser, etc. -->
Linux, Ubuntu 18.04.2 LTS

##### ADDITIONAL INFORMATION
<!--- Describe how this improves the documentation, e.g. before/after situation or screenshots -->
None.
<!--- HINT: You can paste gist.github.com links for larger files -->
rc, stdout, stderr = self._exec_psrp_script(setup_script,
                                                    use_local_scope=False,
                                                    force_stop=True)
        if rc != 0:
            raise AnsibleError("failed to setup file stream for fetch '%s': %s"
                               % (out_path, to_native(stderr)))
        elif stdout.strip() == '[DIR]':
            
            return
        b_out_path = to_bytes(out_path, errors='surrogate_or_strict')
        
        offset = 0
        with open(b_out_path, 'wb') as out_file:
            while True:
                display.vvvvv("PSRP FETCH %s to %s (offset=%d" %
                              (in_path, out_path, offset), host=self._psrp_host)
                rc, stdout, stderr = self._exec_psrp_script(read_script % offset, force_stop=True)
                if rc != 0:
                    raise AnsibleError("failed to transfer file to '%s': %s"
                                       % (out_path, to_native(stderr)))
                data = base64.b64decode(stdout.strip())
                out_file.write(data)
                if len(data) < buffer_size:
                    break
                offset += len(data)
            rc, stdout, stderr = self._exec_psrp_script("$fs.Close()", force_stop=True)
            if rc != 0:
                display.warning("failed to close remote file stream of file "
                                "'%s': %s" % (in_path, to_native(stderr)))
    def close(self):