README: update conda command to new API.

README.md

@@ -35,7 +35,7 @@ Should the procedure described below not work at some point I invite you to chec
 
 ```
 conda create -n cling
-source activate cling
+conda activate cling
 ```
 
 * Install xeus-cling in this environment (and additional Jupyter extension to handle stuff like citations and table of contents).
@@ -49,5 +49,5 @@ conda install xeus-cling notebook jupyter_contrib_nbextensions -c QuantStack -c
 jupyter notebook
 ```
 
-__BEWARE__: I **strongly advise** to use a dedicated environment for the notebook: the ultimate goal is to use a real C++ environment for your project, and the anaconda environment hides your native C++ compiler on your machine.
+__BEWARE__: I **strongly advise** to use a dedicated environment for the notebook: the ultimate goal is to use a real C++ environment for your project, and the anaconda environment hides the native C++ compiler on your machine.