docs(zizmor): drop default-config (#966)

We removed this in 58cb396 but didn't
get rid of the entry in `.github/workflows/reusable-zizmor.md`. Do that
and explain the behaviour in the description of
`always-use-default-config`.

Author: iainlane

.github/workflows/reusable-zizmor.md

@@ -90,16 +90,17 @@ jobs:
 
 ## Inputs
 
-| Name                      | Type    | Description                                                                                                                                                                                                                        | Default Value   | Required |
-| ------------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | -------- |
-| min-severity              | string  | Only show results at or above this severity [possible values: unknown, informational, low, medium, high]                                                                                                                           | medium          | false    |
-| min-confidence            | string  | Only show results at or above this confidence level [possible values: unknown, low, medium, high]                                                                                                                                  | low             | false    |
-| fail-severity             | string  | Fail the build if any result is at or above this severity [possible values: never, any, informational, low, medium, high]                                                                                                          | high            | false    |
-| runs-on                   | string  | The runner to use for jobs. Configure this to use self-hosted runners.                                                                                                                                                             | ubuntu-latest   | false    |
-| default-config            | boolean | The default Zizmor configuration to use. If `always-use-default-config` is `true`, this configuration will always be used. Otherwise, it will be used if the repository does not have a `.github/zizmor.yml` or `zizmor.yml` file. | true            | false    |
-| always-use-default-config | boolean | Whether to always use `default-config`.                                                                                                                                                                                            | false           | false    |
-| github-token              | string  | Use a different token to the default                                                                                                                                                                                               | ${github.token} | false    |
-| extra-args                | string  | Extra arguments to pass into zizmor                                                                                                                                                                                                | ""              | false    |
+| Name                      | Type    | Description                                                                                                                      | Default Value   | Required |
+| ------------------------- | ------- | -------------------------------------------------------------------------------------------------------------------------------- | --------------- | -------- |
+| min-severity              | string  | Only show results at or above this severity [possible values: unknown, informational, low, medium, high]                         | medium          | false    |
+| min-confidence            | string  | Only show results at or above this confidence level [possible values: unknown, low, medium, high]                                | low             | false    |
+| fail-severity             | string  | Fail the build if any result is at or above this severity [possible values: never, any, informational, low, medium, high]        | high            | false    |
+| runs-on                   | string  | The runner to use for jobs. Configure this to use self-hosted runners.                                                           | ubuntu-latest   | false    |
+| always-use-default-config | boolean | Whether to always use the [default configuration]. When `false`, `.zizmor.yml` or `.github/zizmor.yml` will be used, if present. | false           | false    |
+| github-token              | string  | The GitHub token to use when authenticating with the GitHub API                                                                  | ${github.token} | false    |
+| extra-args                | string  | Extra arguments to pass into zizmor                                                                                              | ""              | false    |
+
+[default configuration]: ../zizmor.yml
 
 ## Getting started
 

.github/workflows/reusable-zizmor.yml

@@ -34,7 +34,9 @@ on:
         default: ${{ github.token }}
 
       always-use-default-config:
-        description: Whether to always use the default configuration.
+        description: |
+          Whether to always use the default configuration. When `false`,
+          `.zizmor.yml` or `.github/zizmor.yml` will be used, if present.
         required: false
         type: boolean
         default: false