Wrong hash format used in examples for `proxy` option

[arminru]

Description:

The HTTP output plugin docs use commas as delimiters between entries for the hash used in the proxy config option examples. As per the Logstash config file format documented in https://www.elastic.co/guide/en/logstash/current/configuration-file-structure.html#hash, these would need to be space delimited instead.
Also the plain string the first example would need to be put into quotation marks (proxy => 'http://proxy.org:1234'), I believe.

URL:

https://www.elastic.co/guide/en/logstash/current/plugins-outputs-http.html#plugins-outputs-http-proxy

Proposed change:

Current:

# 1. Proxy host in form: http://proxy.org:1234
# 2. Proxy host in form: {host => "proxy.org", port => 80, scheme => 'http', user => 'username@host', password => 'password'}
# 3. Proxy host in form: {url =>  'http://proxy.org:1234', user => 'username@host', password => 'password'

Expected:

# 1. Proxy host in form: 'http://proxy.org:1234'
# 2. Proxy host in form: {host => "proxy.org" port => 80 scheme => 'http' user => 'username@host' password => 'password'}
# 3. Proxy host in form: {url =>  'http://proxy.org:1234' user => 'username@host' password => 'password'}

Anything else?

See also: logstash-plugins/logstash-mixin-http_client#47