chore(docs): update install documentation

README.md

@@ -54,6 +54,16 @@ The recommended way to install the latest release is to use pip:
 pip install manim-slides
 ```
 
+Optionally, you can also install Manim or ManimGL using extras[^1]:
+
+```bash
+pip install manim-slides[manim]   # For Manim
+# or
+pip install manim-slides[manimgl] # For ManimGL
+```
+
+[^1]: NOTE: you still need to have Manim or ManimGL platform-specific dependencies installed on your computer.
+
 ### Install From Repository
 
 An alternative way to install Manim Slides is to clone the git repository, and install from there: read the [contributing guide](https://eertmans.be/manim-slides/contributing/workflow.html) to know how.

docs/source/contributing/workflow.md

@@ -30,6 +30,32 @@ With Poetry, installation becomes straightforward:
 poetry install
 ```
 
+This, however, only installs the minimal set of dependencies to run the package.
+
+If you would like to install Manim or ManimGL, as documented in the [quickstart](../quickstart),
+you can use the `--extras` option:
+
+```bash
+poetry install --extras manim   # For Manim
+# or
+poetry install --extras manimgl # For ManimGL
+```
+
+Additionnally, Manim Slides comes with group dependencies for development purposes:
+
+```bash
+poetry install --with dev  # For linters and formatters
+# or
+poetry install --with docs # To build the documentation locally
+```
+
+Another group is `test`, but it is only used for
+[GitHub actions](https://github.com/jeertmans/manim-slides/blob/main/.github/workflows/test_examples.yml).
+
+:::{note}
+You can combine any number of groups or extras when installing the package locally.
+:::
+
 ## Running commands
 
 As modules were installed in a new Python environment, you cannot use them directly in the shell.