installation docs: add--no-channel-priority when installing from conda-forge

docs/developer-guide.md

@@ -143,9 +143,16 @@ Install the necessary Python dependencies using the conda package manager:
 ```
 >> conda install setuptools_scm future h5py pytables pytest nose sphinx
 >> conda install scipy pandas matplotlib cython xlrd coverage xlwt openpyxl psutil
->> conda install -c https://conda.anaconda.org/conda-forge pyscaffold pytest-cov
+>> conda install -c https://conda.anaconda.org/conda-forge pyscaffold pytest-cov --no-channel-priority
 ```
 
+Note that ```--no-channel-priority``` avoids that newer packages from the
+```conda-forge``` will be used instead of those from the default ```anaconda```
+channel. Depending on which packages get overwritten, this might brake your
+Anaconda root environment. As such, using ```--no-channel-priority``` should be
+be used for safety (especially when operating from the root environment).
+
+
 ## Get wetb
 
 Copy the https - link on the front page of your fork of wetb

docs/install.md

@@ -9,7 +9,7 @@ Install the necessary Python dependencies using the ```conda``` package manager:
 ```
 conda install setuptools_scm future h5py pytables pytest nose sphinx blosc
 conda install scipy pandas matplotlib cython xlrd coverage xlwt openpyxl psutil
-conda install -c https://conda.anaconda.org/conda-forge pyscaffold pytest-cov
+conda install -c https://conda.anaconda.org/conda-forge pyscaffold pytest-cov --no-channel-priority
 ```
 
 Now you can install ```wetb``` with ```pip``` (there is no ```conda``` package