[NWC] Add get_budget command for per-connection budget limits.

47.md

@@ -373,6 +373,33 @@ Response:
 }
 ```
 
+### `get_budget`
+
+Budgets can be used to limit the amount of funds that can be spent by a connection in a given time period.
+Budgets are optional and can be set by the user if their wallet supports it. Support for this command indicates
+that the wallet supports user-configured budgets. The budget will be reset at the `renews_at` timestamp.
+
+Request:
+```jsonc
+{
+ "method": "get_budget",
+ "params": {
+ }
+}
+```
+
+Response:
+```jsonc
+{
+ "result_type": "get_budget",
+ "result": {
+ "remaining_budget_msats": 10000,
+ "total_budget_msats": 100000,
+ "renews_at": 1693876973, // timestamp in seconds since epoch
+ }
+}
+```
+
 ### `get_info`
 
 Request: