Updated HTTP request API (markdown)

HTTP-request-API.md

@@ -76,6 +76,19 @@ Parameter | Value Range | Description | Since Version
 &MS= | 0 to 16(String 0..64) | Save API macro | 0.5.0
 &M= | 0 to 16 | Apply macro | 0.5.0
 
+## Segments
+It is highly recommended to use the [JSON API](https://github.com/Aircoookie/WLED/wiki/JSON-API) when dealing with Segments.
+
+Parameter | Value Range | Description | Since Version
+| --- | --- | --- | --- |
+&SM= | 0 to 9 | Set the main segment (values are reported to XML) | 0.9.0
+&SS= | 0 to 9 | Select segment to apply THIS api call to | 0.9.0
+&SV= | 0 or 1 | Set segment selected | 0.9.0
+&S= | 0 to ledcount-1 | Set segment start | 0.9.0
+&S2= | 0 to ledcount | Set segment stop | 0.9.0
+&GP= | 1 to 255 | Set segment grouping | 0.9.1
+&SP= | 0 to 255 | Set segment spacing | 0.9.1
+
 ## General and Experimental
 
 Parameter | Value Range | Description | Since Version