docs(pii_masking.md): add pii masking to proxy docs

docs/my-website/docs/proxy/pii_masking.md

@@ -0,0 +1,30 @@
+import Image from '@theme/IdealImage';
+
+# PII Masking
+
+LiteLLM supports [Microsoft Presidio](https://github.com/microsoft/presidio/) for PII masking. 
+
+## Step 1. Add env
+
+```bash
+export PRESIDIO_ANALYZER_API_BASE="http://localhost:5002"
+export PRESIDIO_ANONYMIZER_API_BASE="http://localhost:5001"
+```
+
+## Step 2. Set it as a callback in config.yaml
+
+```yaml
+litellm_settings: 
+    litellm.callbacks = ["presidio"] 
+```
+
+## Start proxy 
+
+```
+litellm --config /path/to/config.yaml
+```
+
+
+This will mask the input going to the llm provider
+
+<Image img={require('../../img/presidio_screenshot.png')} />

docs/my-website/sidebars.js

@@ -116,6 +116,7 @@ const sidebars = {
         "proxy/model_management",
         "proxy/health",
         "proxy/debugging",
+        "proxy/pii_masking",
         {
           "type": "category",
           "label": "🔥 Load Balancing",