docs: minor spoolman updates

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

docs/configuration.md

@@ -2623,6 +2623,9 @@ Front ends can also utilize this config to provide a built-in management tool.
 [spoolman]
 server: http://192.168.0.123:7912
 #   URL to the Spoolman instance. This parameter must be provided.
+sync_rate: 5
+#   The interval, in seconds, between sync requests with the
+#   Spoolman server.  The default is 5.
 ```
 
 ## Include directives

docs/web_api.md

@@ -5308,7 +5308,7 @@ JSON-RPC request:
 ```json
 {
     "jsonrpc": "2.0",
-    "method": "spoolman.post_proxy",
+    "method": "spoolman.proxy",
     "params": {
         "request_method": "POST",
         "path": "/v1/spool",