Simplify install instructions.

Author: jasongrout

docs/source/user_install.md

@@ -5,7 +5,7 @@ Users can install the current version of **ipywidgets** with
 [pip](https://pip.pypa.io/en/stable/) or
 [conda](https://conda.readthedocs.io/en/latest/).
 
-In most cases, installing the Python `ipywidgets` package will also automatically configure classic Jupyter Notebook and JupyterLab 3.0 to display ipywidgets. With pip, do:
+In most cases, installing the Python `ipywidgets` package will also automatically configure classic Jupyter Notebook and JupyterLab 3.x to display ipywidgets. With pip, do:
 
 ``` bash
 pip install ipywidgets
@@ -17,61 +17,52 @@ or with conda, do:
 conda install -c conda-forge ipywidgets
 ```
 
-Installing in classic Jupyter Notebook
---------------------------------------
-
-Most of the time, installing `ipywidgets` automatically configures Jupyter Notebook to use widgets. The `ipywidgets` package does this by depending on the `widgetsnbextension` package, which configures the classic Jupyter Notebook to display and use widgets. If you have an old version of Jupyter Notebook installed, you may need to manually enable the ipywidgets notebook extension with:
-
-```bash
-jupyter nbextension enable --py widgetsnbextension
-```
-
-When using [virtualenv](https://virtualenv.pypa.io/en/stable/) and working in
-an activated virtual environment, the ``--sys-prefix`` option may be required
-to enable the extension and keep the environment isolated (i.e.
-``jupyter nbextension enable --py widgetsnbextension --sys-prefix``).
+Installing in JupyterLab 3.x
+----------------------------
 
+Most of the time, installing `ipywidgets` automatically configures JupyterLab 3.x to use widgets. The `ipywidgets` package does this by depending on the `jupyterlab_widgets` package, which configures JupyterLab 3 to display and use widgets. 
 
-If your Jupyter Notebook and the IPython kernel are installed in different
+If JupyterLab and the IPython kernel are installed in different
 environments (for example, separate environments are providing different
 Python kernels), then the installation requires two steps:
 
-1. Install the `widgetsnbextension` package in the environment
-containing the Jupyter Notebook server.
+1. Install the `jupyterlab_widgets` package in the environment containing JupyterLab.
 2. Install `ipywidgets` in each kernel's environment that will use ipywidgets.
 
-For example, if using conda environments, with Jupyter Notebook installed on the 
-`base` environment and the kernel installed in an environment called `py36`,
+For example, if using conda environments, with JupyterLab installed on the 
+`base` environment and the kernel installed in an environment called `pyenv`,
 the commands are:
 
 ```bash
-conda install -n base -c conda-forge widgetsnbextension
-conda install -n py36 -c conda-forge ipywidgets
+conda install -n base -c conda-forge jupyterlab_widgets
+conda install -n pyenv -c conda-forge ipywidgets
 ```
 
-Installing in JupyterLab 3.0
-----------------------------
 
-Most of the time, installing `ipywidgets` automatically configures JupyterLab 3.0 to use widgets. The `ipywidgets` package does this by depending on the `jupyterlab_widgets` package, version 1.0, which configures JupyterLab 3 to display and use widgets. 
+Installing in classic Jupyter Notebook
+--------------------------------------
+
+Most of the time, installing `ipywidgets` automatically configures Jupyter Notebook to use widgets. The `ipywidgets` package does this by depending on the `widgetsnbextension` package, which configures the classic Jupyter Notebook to display and use widgets. 
 
-If your JupyterLab and the IPython kernel are installed in different
+If your Jupyter Notebook and the IPython kernel are installed in different
 environments (for example, separate environments are providing different
 Python kernels), then the installation requires two steps:
 
-1. Install the `jupyterlab_widgets` package (version 1.0 or later) in the environment
-containing JupyterLab.
+1. Install the `widgetsnbextension` package in the environment
+containing the Jupyter Notebook server.
 2. Install `ipywidgets` in each kernel's environment that will use ipywidgets.
 
-For example, if using conda environments, with JupyterLab installed on the 
-`base` environment and the kernel installed in an environment called `py36`,
+For example, if using conda environments, with Jupyter Notebook installed on the 
+`base` environment and the kernel installed in an environment called `pyenv`,
 the commands are:
 
 ```bash
-conda install -n base -c conda-forge jupyterlab_widgets
-conda install -n py36 -c conda-forge ipywidgets
+conda install -n base -c conda-forge widgetsnbextension
+conda install -n pyenv -c conda-forge ipywidgets
 ```
 
 
+
 Installing into JupyterLab 1 or 2
 ---------------------------------
 
@@ -103,6 +94,23 @@ running the `jupyter lab clean` command which will remove the staging and
 static directories from the lab directory. The location of the lab directory
 can be queried by executing the command `jupyter lab path` in your terminal.
 
+Installing into classic Jupyter Notebook 5.2 or earlier
+-------------------------------------------------------
+
+If you have an old version of Jupyter Notebook installed (version 5.2 or
+earlier), you may need to manually enable the ipywidgets notebook extension
+with:
+
+```bash
+jupyter nbextension enable --py widgetsnbextension
+```
+
+When using [virtualenv](https://virtualenv.pypa.io/en/stable/) and working in
+an activated virtual environment, the ``--sys-prefix`` option may be required
+to enable the extension and keep the environment isolated (i.e.
+``jupyter nbextension enable --py widgetsnbextension --sys-prefix``).
+
+
 Frequently Asked Questions
 --------------------------