install: add HW pre-reqs and avoid Anaconda

Author: Pablo Panero

docs/install/index.md

@@ -7,18 +7,24 @@ command line tool for creating and updating your instance.
 
 Some system requirements are needed beforehand:
 
-- [Python](https://www.python.org/) (3.6 only)
+- [Python](https://www.python.org/) (3.6.2 only)
 - [nodejs](https://nodejs.org) (8.0.0+) (not needed to preview, only needed to develop)
 - [Docker](https://docs.docker.com/) (1.13.0+)
 - [Docker-Compose](https://docs.docker.com/compose/) (1.17.0+)
 
+!!! warning "Other Python distributions"
+    InvenioRDM works with Python 3.6.2. However, many users have reported errors when running Python from Anaconda.
+
 In addition, make sure the user that will be executing the CLI has access to
 the docker command (i.e. it is not only available for the root user):
 
 ```console
 $ sudo usermod --append --groups docker $USER
 ```
 
+!!! note "Hardware requirements"
+    We usually deploy the RDM in machines that have around 8GB of RAM and at least 4 cores. InvenioRDM can certainly run (for demo purposes) with less, just take into account that you are going to be runing between 4 and 8 containers (among them ES, which is quite demanging).
+
 Once you have installed these requirements, you can install the CLI.
 
 ## Install the CLI