Add documentation for x509 module

Author: mkayontour

doc/role-icingaweb2/module-x509.md

@@ -0,0 +1,62 @@
+## Module x509
+
+### Variables and Configuration
+
+The general module parameter like `enabled` and `source` can be applied here.
+
+| Variable | Value      |
+|----------|------------|
+| enabled  | true/false |
+| source   | package    |
+
+#### Section configuration
+
+The backend database for the module needs to be available and configured at the `icingaweb2_resources` variable.
+
+```
+icingaweb2_modules:
+  x509:
+    source: package
+    enabled: true
+    config:
+      backend:
+        resource: x509
+```
+
+#### Configure SNI Names.
+
+To configure SNIs for a IP address, use the dictionary `sni`.
+
+Example:
+
+```
+icingaweb2_modules:
+  x509:
+    source: package
+    enabled: true
+    config:
+      backend:
+        resource: x509
+    sni:
+      192.168.56.213:
+        hostnames:
+          - icinga.com
+          - test2.icinga.com
+```
+
+#### Import Certificates
+
+To import certificates use the **list** `certificate_files` all files need to be
+available locally beforehand. 
+
+```
+icingaweb2_modules:
+  x509:
+    source: package
+    enabled: true
+    config:
+      backend:
+        resource: x509
+    certificate_files:
+      - /etc/ssl/certs/ca-certificates.crt
+```