Recommend first gpu_use_dp = true (#564)

* Recommend first gpu_use_dp = true

* Add link to issue

* Fix wrong issue

docs/FAQ.md

@@ -58,7 +58,7 @@ Remember this is a free/open community support. We may not be available 24/7 to
 
 - **Question 4**: When using LightGBM GPU, I cannot reproduce results over several runs.
 
-- **Solution 4**: It is a normal issue, there is nothing we/you can do about. For reproducible results, please use CPU version.
+- **Solution 4**: It is a normal issue, there is nothing we/you can do about, you may try to use `gpu_use_dp = true` for reproducibility (see [issue #560](https://github.com/Microsoft/LightGBM/pull/560#issuecomment-304561654)). You may also use CPU version.
 
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