docs: Load Cell Probe Documentation

Add documentation updates for Homing & Probing with load cell probe

Signed-off-by: Gareth Farrington <gareth@waves.ky>

docs/API_Server.md

@@ -380,6 +380,27 @@ and might later produce asynchronous messages such as:
 The "header" field in the initial query response is used to describe
 the fields found in later "data" responses.
 
+### load_cell_probe/dump_taps
+
+This endpoint is used to subscribe to details of probing "tap" events.
+Using this endpoint may increase Klipper's system load.
+
+A request may look like:
+`{"id": 123, "method":"load_cell/dump_force",
+"params": {"sensor": "load_cell", "response_template": {}}}`
+and might return:
+`{"id": 123,"result":{"header":["probe_tap_event"]}}`
+and might later produce asynchronous messages such as:
+```
+{"params":{"tap":'{
+   "time": [118032.28039, 118032.2834, ...],
+   "force": [-459.4213119680034, -458.1640702543264, ...],
+}}}
+```
+
+This data can be used to render:
+* The time/force graph
+
 ### pause_resume/cancel
 
 This endpoint is similar to running the "PRINT_CANCEL" G-Code command.