Added docstring to address 'Scaling of RandImageFilterd transform #6857' (#8055)

Fixes #6857 

### Description

Added docstring to RandImageFilterd method which informs the user that
they need to manually scale the result image when using this method.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [x] In-line docstrings updated.

---------

Signed-off-by: dedeepyasai <dedeepyasai.sai@gmail.com>
Signed-off-by: saelra <rasaelee@gmail.com>
Signed-off-by: Kelvin R <kelvinrbNsc@gmail.com>
Signed-off-by: ken-ni <kennett.vera@gmail.com>
Signed-off-by: Dureti <98233210+DuretiShemsi@users.noreply.github.com>
Signed-off-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: saelra <rasaelee@gmail.com>
Co-authored-by: Kelvin R. <138339140+K-Rilla@users.noreply.github.com>
Co-authored-by: Kelvin R <kelvinrbNsc@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: dedeepyasai <dedeepyasai.sai@gmail.com>
Co-authored-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: Ratanachat Saelee <146144408+Saelra@users.noreply.github.com>
Co-authored-by: Dureti <98233210+DuretiShemsi@users.noreply.github.com>
Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>

Author: 8 people

monai/transforms/utility/dictionary.py

@@ -1714,6 +1714,10 @@ class RandImageFilterd(MapTransform, RandomizableTransform):
             Probability the transform is applied to the data
         allow_missing_keys:
             Don't raise exception if key is missing.
+
+    Note:
+        - This transform does not scale output image values automatically to match the range of the input.
+          The output should be scaled by later transforms to match the input if this is desired.
     """
 
     backend = ImageFilter.backend