MAINT: added timestamp to note about dependency issues of lxml

validation/README.md

@@ -14,6 +14,8 @@ environment for Python2 or Python3 (whichever you prefer) using the [Conda](http
 
 #### Attention
 
+Note from: 2016-12-29
+
 Due to some dependency issues of *lxml*, it has to be installed from within the activated Conda environment. 
 That is why, in the Conda YAML files, the line `- lxml=3.*` is commented out - see also here: [Github issues](https://github.com/conda/conda/issues/4093)
 
@@ -26,7 +28,7 @@ In case you want to use the Conda package manager, you can create the environmen
 $ conda env create -f conda_py3_mdvalid.yml
 ## wait for setup to complete
 $ source activate py3valid
-## next line: workaround solution
+## next line: workaround solution - 2016-12-29
 $ pip install lxml
 ## wait for installation to complete
 ## run the script; see below