Add listing page

Author: cwickham

docs/advanced/environment-vars.qmd

@@ -0,0 +1,59 @@
+---
+title: "Environment Variables"
+summary: Environment variables Quarto inspects and sets
+format: html
+draft: true
+---
+
+## Variables Quarto inspects
+
+These are variables that you can set to control how Quarto renders documents. For example, you can set them explicitly before running `quarto render`:
+
+```{.bash filename="Terminal"}
+export QUARTO_R=/opt/R/4.2.3/bin
+quarto render
+```
+
+You can read about other ways to set environment variables in Quarto Projects in [Environment Variables](/docs/projects/environment.qmd).
+
+| Variable        | Description |
+|-----------------|-------------|
+| `QUARTO_R`      |             |
+| `QUARTO_PYTHON` |             |
+|                 |             |
+
+## Variables Quarto sets
+
+These variables are set by Quarto you can query them. For example, you can query them in an executable code cell:
+
+::: {.panel-tabset}
+
+## R
+
+```r
+Sys.getenv("QUARTO_DOCUMENT_PATH")
+```
+
+## Python
+
+```python
+import os
+print(os.environ["QUARTO_DOCUMENT_PATH"])
+```
+
+## Julia 
+
+```julia
+ENV["QUARTO_DOCUMENT_PATH"]
+```
+
+:::
+
+
+| Variable                  | Description |
+|---------------------------|-------------|
+| `QUARTO_PROJECT_ROOT`     |             |
+| `QUARTO_DOCUMENT_PATH`    |             |
+|                           |             |
+
+

docs/advanced/index.qmd

@@ -0,0 +1,12 @@
+---
+title: "Advanced User Documentation"
+format: html
+search: false
+listing: 
+  type: table
+  fields: [title, summary]
+  field-display-names:
+    summary: Summary
+---
+
+Topics on this page may be of interest to advanced users of Quarto. 

docs/advanced/jupyter/kernel-execution.qmd

@@ -1,6 +1,7 @@
 ---
 title: Jupyter Kernel Execution
 format: html
+summary: How to support Quarto from a Jupyter kernel
 ---
 
 Quarto executes Jupyter notebooks using [`nbclient`](https://github.com/jupyter/nbclient) together with a few additional options