More Positron specific screenshots + dark

Author: cwickham

docs/tools/_code-oss-editors.md

@@ -0,0 +1,11 @@
+
+```{dot}
+//| echo: fenced
+graph G {
+  layout=neato
+  A -- B;
+  B -- C;
+  A -- C;
+  A -- D;
+}
+```

docs/tools/_examples/diagrams.qmd

@@ -8,6 +8,8 @@ jupyter: python3
 
 For a demonstration of a line plot on a polar axis, see @fig-polar.
 
+
+
 ```{python}
 #| label: fig-polar
 #| fig-cap: "A line plot on a polar axis"
@@ -30,3 +32,7 @@ plt.show()
 
 Photo by ALMA (ESO/NAOJ/NRAO)/H. Kim et al. - [Original](https://www.eso.org/public/images/potw1710a/), [CC BY 4.0](https://creativecommons.org/licenses/by/4.0)
 
+$$
+\theta = 2\pi r
+$$
+