Mention #180 in README

as reference for OKEX/Bitmex private channels

README.md

@@ -97,13 +97,13 @@ Listening for live updates of:
 | **Binance**      | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | |
 | **Bitfinex**     | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | |
 | **Bitflyer**     | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :question:         | :question:         | :question:         | |
-| **BitMEX**       | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :construction:     | :construction:     | :construction:     | We are short of maintainers able to review pull requests and provide support for Bitmex, so there is a backlog of pull requests and support is likely broken. Can you help? |
+| **BitMEX**       | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :construction:     | :construction:     | :construction:     | We are short of maintainers able to review pull requests and provide support for Bitmex, so there is a backlog of pull requests and support is likely broken. Can you help? See [#180](https://github.com/bitrich-info/xchange-stream/pull/180) for reference if attempting to add private channel support. |
 | **Bitstamp**     | :heavy_check_mark: | :heavy_check_mark: | :x:                | :question:         | :question:         | :question:         | |
 | **CEX.IO**       | :heavy_check_mark: | :x:                | :x:                | :question:         | :question:         | :question:         | New support, not widely tested  |
 | **Coinbase Pro** | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | |
 | **Coinmate**     | :heavy_check_mark: | :heavy_check_mark: | :x:                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | |
 | **OKCoin**       | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :question:         | :question:         | :question:         | |
-| **OKEx**         | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :question:         | :question:         | :question:         | |
+| **OKEx**         | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :question:         | :question:         | :question:         | See [#180](https://github.com/bitrich-info/xchange-stream/pull/180) for reference if attempting to add private channel support. |
 | **Poloniex**     | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :question:         | :question:         | :question:         | |
 | **Gemini**       | :heavy_check_mark: | :heavy_check_mark: | :x:                | :construction:     | :construction:     | :construction:     | |