python and julia download links

Author: Christopher Doris

docs/src/getting-started.md

@@ -2,8 +2,8 @@
 
 ## You will need
 
-* Julia 1.0 or higher.
-* Python 3.5 or higher.
+* Julia 1.0 or higher — download [here](https://julialang.org/downloads).
+* Python 3.5 or higher — download [here](https://www.python.org/downloads) or set `JULIA_PYTHONCALL_EXE=CONDA` (see below).
 
 ## Install the Julia package `PythonCall`
 
@@ -40,6 +40,8 @@ If Julia and Python are in your PATH, then no further set-up is required.
 Otherwise, the following environment variables control how the package finds these.
 - `JULIA_PYTHONCALL_EXE`: Path to the Python executable. Or the special value `CONDA` which uses
   Python from the default conda environment, or `CONDA:{env}` to use the given environment.
+  In this case, if `conda` is not detected then `Conda.jl` will automatically install
+  [`miniconda`](https://docs.conda.io/en/latest/miniconda.html) in your Julia depot.
 - `JULIA_PYTHONCALL_LIB`: Path to the Python library. Normally this is inferred from the Python
   executable, but can be over-ridden.
 - `PYTHON_JULIACALL_EXE`: Path to the Julia executable.