add ClickHouse to onprem database

# Conflicts:
#	docs/nodes/onprem.md

Add Celery to onprem.queue #68

Signed-off-by: Slach <bloodjazman@gmail.com>

Signed-off-by: Slach <bloodjazman@gmail.com>

Add Dgraph, JanusGraph, Scylla to onprem.database

Add Git/GitLab/Github to onprem.vcs section #58

Add Spinnaker

Add polyaxon

fix: graph_attr example

`graphviz` only support string or byte-like objects as value in attributes. The example was passing `fontsize` as `int` that throws `TypeError`.

Just fixing the example

Add resizing to contributing

Add PFSense and VyOS router distribution logos

Support Apache Beam

This PR adds information on how to resize your images when
contributing.

It also applies a few formatting changes such as:

- Using named links to reduce clutter
- Folding the text at 80 characters for command line users
- Removing dollar signs in codeblocks if no command output is provided
  [MD014][md014]

[md014]: https://github.com/markdownlint/markdownlint/blob/master/docs/RULES.md#md014---dollar-signs-used-before-commands-without-showing-output

Update CONTRIBUTING.md

Fix typo

* Initial commit

* feat(gcp): add identity-aware proxy

Co-authored-by: McSly <sylvain.mielot@gmail.com>

feat(security): add Trivy

* Edges support

* Documentation and additional style attribute

* Better example and review changes

* Fix xlabel

* Fix docs

* Add Edge default properties

* Fix edge docs

Co-authored-by: Andrew Selivanov <a_selivanov@wargaming.net>

feat(aws - customer engagement): added Customer Engagement services

Included Amazon Connect, Amazon Pinpoint and Amazon Simple Email Service (SES)