improve documentation (#211)

* adding skeleton for documentation

* fixing typos

* adding skeleton for next gen documentation (#199)

* adding skeleton for documentation

* fixing typos

* Documentation (#201)

* adding skeleton for documentation

* fixing typos

* Config-editor-ui: some css fixes + testing deployment + title validation + regex links (#200)

Co-authored-by: Celie Valentiny <Celie.Valentiny@gresearch.co.uk>

* improve introduction

* updated documentation

* improved introduction

* adding arichtecture image

* resize image

* fixing image

* adding parser_flow image

* adding router parsing image

* making urls clickable

* Fixing typos based on review

* adding siembol response work in progress documentation

Co-authored-by: Celie Valentiny <Celie.Valentiny@gresearch.co.uk>

docs/deployment/how-tos/how_to_setup_github_webhook.md

@@ -0,0 +1,35 @@
+# How to set-up a github webhook
+The synchronisation of service configurations are stored in git repositories with zookeeper nodes is implemented in siembol in config editor rest service.
+## Siembol config editor rest rest endpoint for webhooks
+Find a hostname of siembol config editor rest and prepare url. 
+### Url parameters
+- serviceNames - Comma-separated list of service names or ```all``` if the hook is for all services
+- syncType - Type of synchronisation that should be triggered by the hook
+    - one from ```ALL```, ```RELEASE```, ```ADMIN_CONFIG```
+
+```
+Example of url:
+https://config-editor/api/v1/sync/webhook?serviceNames=alert&syncType=ALL
+```
+## Setting a webhook in a github repository
+For a git repository you should recognise: 
+- services which configurations are stored in a git repository
+- type of configurations that are stored in the git repository
+### Prepare and test url
+You can prepare url using above example or by swagger
+```
+Example of swagger url:
+https://config-editor-rest/swagger-ui.html
+```
+Ensure that the prepared url is accessible form the github server.
+### Set a webhook url in github
+To set up a webhook, go to the settings page of your repository or organization in github. From there, click Webhooks, then Add webhook url with push event.
+### Set the content type
+Set the content type as ```application/json```
+### Set the github secret (optional)
+Setting a webhook secret allows you to ensure that  POST requests sent to siembol are from GitHub. 
+#### Set the secret for verification in config editor rest application properties 
+The verification of webhook signature is computed only if is set the secret in the application properties of config editor rest. Otherwise this check is skipped.
+```
+config-editor.gitWebhookSecret=your secret provided in github
+```