Add initial tracing docs (#1731)

Co-authored-by: RJ Beers <[email protected]>

Author: kralicky

content/docs/reference/img/tracing/auth-flow-2.png

@@ -554,7 +554,7 @@
     "services": []
   },
   "tracing-otlp-protocol": {
-    "id": "tracing-otlp-endpoint",
+    "id": "tracing-otlp-protocol",
     "title": "Tracing Provider",
     "description": "Transport protocol to be used for OTLP trace data.",
     "path": "/tracing",
@@ -567,6 +567,13 @@
     "path": "/tracing",
     "services": []
   },
+  "tracing-headers": {
+    "id": "tracing-headers",
+    "title": "OTLP Export Headers",
+    "description": "Key=Value headers to add to all outgoing trace export requests",
+    "path": "/tracing",
+    "services": []
+  },
   "use-proxy-protocol": {
     "id": "use-proxy-protocol",
     "title": "Use Proxy Protocol",

content/docs/reference/img/tracing/auth-flow.png

@@ -125,6 +125,7 @@
     "pomerium",
     "posix",
     "proto",
+    "protobuf",
     "proxied",
     "proxying",
     "psql",