Add patterns folder and custom-pattern-example file to helk-logstash …

[colinrubbert]

…pipeline folder for easier customization and extensibility of the HELK stack.

What is this PR for? Adding a patterns folder to the helk-logstash pipeline to allow for custom patterns for pipeline/*.conf files that do not already have a pattern shipped by default with logstash.

Adding this to the pipeline folder eliminates the need to edit any other part of the HELK stack reducing the obfuscation and complication of customizing docker containers while providing an ability for people to further enhance HELK to their desired needs.

What type of PR is it? [Feature Request]

How should this be tested? This can be tested with a custom .conf file in the pipeline folder using a custom pattern variable that is not provided by logstash out of the box. I can provide a custom .conf file and custom pattern file. My plan will be to add documentation to provide a use-case example using pi-hole logs, pi-hole custom .conf, and dns-pihole custom pattern file.

Questions:

• Do the licenses files need update? No
• Are there breaking changes for older versions? No
• Does this needs documentation? Not necessarily, however, I will be adding further documentation in a later PR with a use case example that will provide further explanation of the patterns folder and custom patterns. Custom patterns are documented within the official ELK documentation. Documentation for HELK would be in service of extending HELK to fit end-users environments via use-case examples.

[Cyb3rWard0g]

Thank you very much @colinrubbert ! I really appreciate it !