feat: add support for .zizmor.yml files

docs/configuration.md

@@ -27,8 +27,9 @@ configuration files in the following order of precedence:
    explicitly, the config file does *not* need to be named `zizmor.yml`.
 1. `${CWD}/.github/zizmor.yml`
 1. `${CWD}/zizmor.yml`
+1. `${CWD}/.zizmor.yml`
 
-For the last two discovery methods, `${CWD}` is the current working directory,
+For the folder-tree-based discovery methods, `${CWD}` is the current working directory,
 i.e. the directory that `zizmor` was executed from.
 
 Only one configuration file is ever loaded. In other words: if both
@@ -59,7 +60,7 @@ where `filename.yml` is the base filename of the workflow, and `line` and
 location to ignore. If one or both are absent, then the rule applies to the
 entire file or entire line.
 
-By example, here is a configuration file with two different audit ignore
+For example, here is a configuration file with two different audit ignore
 rule groups:
 
 ```yaml title="zizmor.yml"

src/config.rs

@@ -84,22 +84,18 @@ impl Config {
                 // If the user didn't pass a config path explicitly with
                 // `--config`, then we attempt to discover one relative to $CWD
                 // Our procedure is to first look for `$CWD/.github/zizmor.yml`,
-                // then `$CWD/zizmor.yml`, and then bail.
+                // then `$CWD/zizmor.yml`, then `$CWD/.zizmor.yml`, and then bail.
                 let cwd = std::env::current_dir()
                     .with_context(|| "config discovery couldn't access CWD")?;
 
-                let path = cwd.join(".github").join("zizmor.yml");
-                if path.is_file() {
-                    serde_yaml::from_str(&fs::read_to_string(path)?)?
-                } else {
-                    let path = cwd.join("zizmor.yml");
+                for path in &[".github/zizmor.yml", "zizmor.yml", ".zizmor.yml"] {
+                    let path = cwd.join(path);
                     if path.is_file() {
                         serde_yaml::from_str(&fs::read_to_string(path)?)?
-                    } else {
-                        tracing::debug!("no config discovered; loading default");
-                        Config::default()
                     }
                 }
+                tracing::debug!("no config discovered; loading default");
+                Config::default()
             }
         };