update grid search doc (#1486)

* same meaning of 'q' with other tuners
* not longer support qloguniform, support randint 

docs/en_US/Tuner/GridsearchTuner.md

@@ -3,4 +3,6 @@ Grid Search on NNI
 
 ## Grid Search
 
-Grid Search performs an exhaustive searching through a manually specified subset of the hyperparameter space defined in the searchspace file. Note that the only acceptable types of search space are `choice`, `quniform`, `qloguniform`. **The number `q` in `quniform` and `qloguniform` has special meaning (different from the spec in [search space spec](../Tutorial/SearchSpaceSpec.md)). It means the number of values that will be sampled evenly from the range `low` and `high`.**
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+Grid Search performs an exhaustive searching through a manually specified subset of the hyperparameter space defined in the searchspace file. 
+
+Note that the only acceptable types of search space are `choice`, `quniform`, `randint`. 
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