Docs: General fixes and improvements (#662)

* Restore security docs (non-versioned), fix troubleshooting section

* Fix links in security page, add prerequisites to deploying jenkins

* Minor fixes in troubleshooting section

* Fix order of main sections

* Remove tools guide from developer guide

* Fix order of Getting Started guide parts

website/content/en/docs/Security/_index.md

@@ -0,0 +1,70 @@
+---
+title: "Security"
+linkTitle: "Security"
+weight: 3
+date: 2019-08-05
+description: >
+    Jenkins security and hardening out of the box
+---
+
+By default **Jenkins Operator** performs an initial security hardening of Jenkins instance
+via groovy scripts to prevent any security gaps.
+
+## Jenkins Access Control
+
+Currently **Jenkins Operator** generates a username and random password and stores them in a Kubernetes Secret.
+However any other authorization mechanisms are possible and can be done via groovy scripts or configuration as code plugin.
+For more information take a look at the section on [customizing Jenkins](/kubernetes-operator/docs/getting-started/latest/customizing-jenkins/).
+
+Any change to Security Realm or Authorization requires that user called `jenkins-operator` must have admin rights
+because **Jenkins Operator** calls Jenkins API.
+
+## Jenkins Hardening
+
+The list below describes all the default security setting configured by the **Jenkins Operator**:
+
+- basic settings - use `Mode.EXCLUSIVE` - Jobs must specify that they want to run on master node
+- enable CSRF - Cross Site Request Forgery Protection is enabled
+- disable usage stats - Jenkins usage stats submitting is disabled
+- enable master access control - Slave to Master Access Control is enabled
+- disable old JNLP protocols - `JNLP3-connect`, `JNLP2-connect` and `JNLP-connect` are disabled
+- disable CLI - CLI access of `/cli` URL is disabled
+- configure kubernetes-plugin - secure configuration for Kubernetes plugin
+
+If you would like to dig a little bit into the code, take a look [here][base-configuration].
+
+## Jenkins API
+
+The **Jenkins Operator** generates and configures Basic Authentication token for Jenkins Go client
+and stores it in a Kubernetes Secret.
+
+## Kubernetes
+
+Kubernetes API permissions are limited by the following roles:
+
+- [jenkins-operator role][jenkins-operator-role]
+- [Jenkins Controller (Master) role][jenkins-controller-role]
+
+Since **Jenkins Operator** must be able to grant permission for its deployed Jenkins masters
+to spawn pods (the `Jenkins Master role` above),
+the operator itself requires permission to create RBAC resources (the `jenkins-operator role` above).
+
+Deployed this way, any subject which may create a Pod (including a Jenkins job) may
+assume the `jenkins-operator` role by using its' ServiceAccount, create RBAC rules, and thus escape its granted permissions.
+Any namespace to which the `jenkins-operator` is deployed must be considered to implicitly grant all
+possible permissions to any subject which can create a Pod in that namespace.
+
+To mitigate this issue, **Jenkins Operator** should be deployed in one namespace, and the Jenkins CR should be created in
+a separate namespace. For instructions on how to deploy Jenkins Operator and Jenkins in separate namespaces, head over
+to the [Separate namespaces](/kubernetes-operator/docs/getting-started/latest/separate-namespaces) section of Getting Started
+guide.
+
+
+## Report a Security Vulnerability
+
+If you find a vulnerability or any misconfiguration in Jenkins, please report it in the [issues](https://github.com/jenkinsci/kubernetes-operator/issues).
+
+[jenkins-operator-role]:https://github.com/jenkinsci/kubernetes-operator/blob/v0.6.0/deploy/all-in-one-v1alpha2.yaml
+[jenkins-controller-role]:https://github.com/jenkinsci/kubernetes-operator/blob/v0.6.0/pkg/configuration/base/resources/rbac.go
+[base-configuration]:https://github.com/jenkinsci/kubernetes-operator/blob/master/pkg/configuration/base/resources/base_configuration_configmap.go
+[issues]:https://github.com/jenkinsci/kubernetes-operator/issues