add basic theme api docs to README.md

temporary - will move to quartodoc later

Author: gordonwoodhull

README.md

@@ -4,3 +4,36 @@ Python interface to the Quarto CLI (https://quarto-dev/quarto-cli).
 
 
 
+## theme helpers
+
+`quarto-python` contains theme helpers to do basic background/foreground theming of plots and tables
+
+The `theme_colors_*` functions take background and foreground colors:
+
+| parameter | description |
+| --------- | ----------- |
+| `bg` | background color |
+| `fg` | foreground color |
+
+The `theme_brand_*` functions take a [brand.yml](https://posit-dev.github.io/brand-yml/) file:
+
+| parameter | description |
+| --------- | ----------- |
+| `brand_yml` | path to **brand.yml** file |
+
+Available theme helpers:
+
+| colors | brand |
+| --------- | ----------- |
+| `theme_colors_altair` | `theme_brand_altair` |
+| `theme_colors_bokeh` | `theme_brand_bokeh` |
+| `theme_colors_great_tables` | `theme_brand_great_tables` |
+| `theme_colors_matplotlib` | `theme_brand_matplotlib` |
+| `theme_colors_plotnine` | `theme_brand_plotnine` |
+| `theme_colors_plotly` | `theme_brand_plotly` |
+| `theme_colors_pygal` | `theme_brand_pygal` |
+| `theme_colors_seaborn` | `theme_brand_seaborn` |
+
+The usage of the returned object or function depends on the package. See this repo for usage examples:
+
+https://github.com/quarto-dev/quarto-examples/tree/main/renderings