docs/admin: break per-environment details into their own pages (#292)

Signed-off-by: Xe Iaso <me@xeiaso.net>

docs/docs/admin/environments/kubernetes.mdx

@@ -0,0 +1,128 @@
+# Kubernetes
+
+When setting up Anubis in Kubernetes, you want to make sure that you thread requests through Anubis kinda like this:
+
+```mermaid
+---
+title: Anubis embedded into workload pods
+---
+
+flowchart LR
+    T(User Traffic)
+
+    IngressController(IngressController)
+
+    subgraph Service
+        AnPort(Anubis Port)
+        BPort(Backend Port)
+    end
+
+    subgraph Pod
+        An(Anubis)
+        B(Backend)
+    end
+
+    T -->  IngressController
+    IngressController --> AnPort
+    AnPort --> An
+    An --> B
+```
+
+Anubis is lightweight enough that you should be able to have many instances of it running without many problems. If this is a concern for you, please check out [ingress-anubis](https://github.com/jaredallard/ingress-anubis?ref=anubis.techaro.lol).
+
+This example makes the following assumptions:
+
+- Your target service is listening on TCP port `5000`.
+- Anubis will be listening on port `8080`.
+
+Adjust these values as facts and circumstances demand.
+
+Create a secret with the signing key Anubis should use for its responses:
+
+```
+kubectl create secret generic anubis-key \
+  --namespace default \
+  --from-literal=ED25519_PRIVATE_KEY_HEX=$(openssl rand -hex 32)
+```
+
+Attach Anubis to your Deployment:
+
+```yaml
+containers:
+  # ...
+  - name: anubis
+    image: ghcr.io/techarohq/anubis:latest
+    imagePullPolicy: Always
+    env:
+      - name: "BIND"
+        value: ":8080"
+      - name: "DIFFICULTY"
+        value: "4"
+      - name: ED25519_PRIVATE_KEY_HEX
+        valueFrom:
+          secretKeyRef:
+            name: anubis-key
+            key: ED25519_PRIVATE_KEY_HEX
+      - name: "METRICS_BIND"
+        value: ":9090"
+      - name: "SERVE_ROBOTS_TXT"
+        value: "true"
+      - name: "TARGET"
+        value: "http://localhost:5000"
+      - name: "OG_PASSTHROUGH"
+        value: "true"
+      - name: "OG_EXPIRY_TIME"
+        value: "24h"
+    resources:
+      limits:
+        cpu: 750m
+        memory: 256Mi
+      requests:
+        cpu: 250m
+        memory: 256Mi
+    securityContext:
+      runAsUser: 1000
+      runAsGroup: 1000
+      runAsNonRoot: true
+      allowPrivilegeEscalation: false
+      capabilities:
+        drop:
+          - ALL
+      seccompProfile:
+        type: RuntimeDefault
+```
+
+Then add a Service entry for Anubis:
+
+```yaml
+# ...
+spec:
+  ports:
+    # diff-add
+    - protocol: TCP
+      # diff-add
+      port: 8080
+      # diff-add
+      targetPort: 8080
+      # diff-add
+      name: anubis
+```
+
+Then point your Ingress to the Anubis port:
+
+```yaml
+  rules:
+  - host: git.xeserv.us
+    http:
+      paths:
+      - pathType: Prefix
+        path: "/"
+        backend:
+          service:
+            name: git
+            port:
+              # diff-remove
+              name: http
+              # diff-add
+              name: anubis
+```