Add Cidaas doc page

docs/docs/configuration/providers/cidaas.md

@@ -0,0 +1,37 @@
+---
+id: cidaas
+title: Cidaas
+---
+
+Cidaas is an Identity as a Service (IDaaS) solution that provides authentication and authorization services. 
+It supports various protocols including OpenID Connect, OAuth 2.0, and SAML.
+
+However, Cidaas provides groups and their roles as hierarchical claims, which are not supported by oauth2-proxy yet.
+The Cidaas provider transforms the hierarchical claims into a flat list of groups, which can be used by oauth2-proxy.
+
+Example of groups and roles in Cidaas:
+
+```json
+{
+  "groups": [
+    {
+      "groupId": "group1",
+      "roles": ["role1", "role2"]
+    },
+    {
+      "groupId": "group2",
+      "roles": ["role3"]
+    }
+  ]
+}
+```
+
+This will be transformed into a flat list of groups:
+
+```json
+{
+  "groups": ["group1:role1", "group2:rol2", "group2:role3"]
+}
+```
+
+Apart from that the Cidaas provider inherits all the features of the [OpenID Connect provider](./openid-connect.md).