docs: mention feedrattler (#1644)

Author: ruben-arts

docs/converting_from_conda_build.md

@@ -180,3 +180,24 @@ The `script` tests also take a `requirements` section with `run` and `build`
 requirements. The `build` requirements can be used to install emulators and
 similar tools that need to run to execute tests in a cross-compilation
 environment.
+
+# Automatic feedstock conversion
+
+Use the tool [`feedrattler`](https://github.com/hadim/feedrattler) by [hadim](https://github.com/hadim) to go directly from an existing conda-forge v0 recipe feedstock to the new v1 recipe used by rattler-build.
+
+You can install and use it directly by running `pixi exec`:
+```
+pixi exec feedrattler my-awesome-feedstock
+```
+
+It uses the `conda-recipe-manager` for the generation of the recipe and `gh` or a `GITHUB_TOKEN` for creating the conversion PR in your name.
+
+Alternative installation:
+```
+# Globally install the tool
+pixi global install feedrattler
+# or in a workspace
+pixi add feedrattler
+# or using conda/mamba
+conda install -c conda-forge feedrattler
+```