Update all_transformers.md

Author: EssamWisam

docs/src/transformers/all_transformers.md

@@ -2,6 +2,7 @@
 | Transformer | Brief Description | 
 |:----------:|:----------:|
 | [Standardizer](@ref) | Transforming columns of numerical features by standardization | 
+| [UnivariateStandardizer](@ref) | Apply standardization given a single vector |
 | [UnivariateBoxCoxTransformer](@ref) | Apply BoxCox transformation given a single vector | 
 | [InteractionTransformer](@ref) | Transforming columns of numerical features to create new interaction features |
 | [UnivariateDiscretizer](@ref) | Discretize a continuous vector into an ordered factor | 
@@ -29,6 +30,10 @@
 MLJTransforms.Standardizer
 ```
 
+```@docs; canonical = false
+MLJTransforms.UnivariateStandardizer
+```
+
 ```@docs; canonical = false
 MLJTransforms.UnivariateBoxCoxTransformer
 ```