Add mention of PyPI to Wave docs

Signed-off-by: Phil Ewels <[email protected]>

docs/conda.md

@@ -62,6 +62,7 @@ The usual Conda package syntax and naming conventions can be used. The version o
 
 The name of the channel where a package is located can be specified prefixing the package with the channel name as shown here `bioconda::bwa=0.7.15`.
 
+(conda-env-files)=
 ### Use Conda environment files
 
 Conda environments can also be defined using one or more Conda environment files. This is a file that lists the required packages and channels structured using the YAML format. For example:
@@ -96,6 +97,7 @@ process foo {
 The environment file name **must** have a `.yml` or `.yaml` extension or else it won't be properly recognised.
 :::
 
+(conda-pypi)=
 ### Python Packages from PyPI
 
 Conda environment files can also be used to install Python packages from the [PyPI repository](https://pypi.org/)), through the `pip` package manager (which must also be explicitly listed as a required package):

docs/wave.md

@@ -90,6 +90,8 @@ conda.channels = 'conda-forge,bioconda'
 ```
 :::
 
+Packages from the [Python Package Index](https://pypi.org/) can also be used by using a Conda `environment.yml` file - see the documentation about {ref}`Conda and PyPI <conda-pypi>` for details.
+
 (wave-singularity)=
 
 ### Build Singularity native images