doc: explain correct globbing behavior

fix #749

Author: HerringtonDarkholme

website/guide/project/lint-rule.md

@@ -146,7 +146,7 @@ ignores:
 - "tests/config/**"
 ```
 
-`ignores` and `files` can be used together. But `files` will take precedence over `ignores`.
+`ignores` and `files` can be used together. `ignores` will be tested before `files`. See [reference](/reference/yaml.html#ignores) for more details.
 
 :::warning Don't add `./`
 

website/reference/yaml.md

@@ -232,15 +232,21 @@ Please also see [label guide](/guide/project/lint-rule.html#customize-code-highl
 * type: `Array<String>`
 * required: false
 
-Glob patterns to specify that the rule only applies to matching files. It takes priority over `ignores`.
+Glob patterns to specify that the rule only applies to matching files. It is tested if `ignores` does not exist or a file does not match any `ignores` glob.
+
+**Example:**
 
-Example:
 ```yaml
 files:
   - src/**/*.js
   - src/**/*.ts
 ```
 
+:::warning Don't add `./`
+Be sure to remove `./` to the beginning of your rules. ast-grep will not recognize the paths if you add `./`.
+:::
+
+
 ### `ignores`
 * type: `Array<String>`
 * required: false
@@ -251,18 +257,20 @@ ignores:
   - test/**/*.ts
 ```
 
-Glob patterns that exclude rules from applying to files. It is superseded by `files` if both are specified.
+Glob patterns that exclude rules from applying to files. A file is tested against `ignores` list before matching `files`.
+
+A typical globing process works as follows:
+
+1. If `ignores` is configured, a file will be skipped if it matches any of the glob in the list(`files` will not be tested).
+2. If `files` is configured, a file will be included if and only if it matches one of the glob in the list.
+3. If neither `ignores`/`files` is configured, a file is included by default.
 
 :::warning `ignores` in YAML is different from `--no-ignore` in CLI
 ast-grep respects common ignore files like `.gitignore` and hidden files by default.
 To disable this behavior, use [`--no-ignore`](/reference/cli.html#scan) in CLI.
 `ignores` is a rule-wise configuration that only filters files that are not ignored by the CLI.
 :::
 
-:::warning Don't add `./`
-Be sure to remove `./` to the beginning of your rules. ast-grep will not recognize the paths if you add `./`.
-:::
-
 
 ## Other