docs: update document

Signed-off-by: ktro2828 <kotaro.uetake@tier4.jp>

Author: ktro2828

docs/cli/t4sanity.md

@@ -93,8 +93,24 @@ With `-f; --fix` option enables to fix issues automatically:
 ```shell
 # Fix issues automatically
 t4sanity <DATA_ROOT> --fix
+
+>>>Sanity checking...: 1it [00:00,  9.70it/s]
+
+=== DatasetID: dataset1 ===
+  ...
+  REC007: --> FIXED🎉
+     - All categories either must have an 'index' set or all have a 'null' index.
+  ...
+
++-----------+---------+--------+--------+---------+----------+-------+
+| DatasetID | Version | Passed | Failed | Skipped | Warnings | Fixed |
++-----------+---------+--------+--------+---------+----------+-------+
+| dataset1  |    0    |   49   |   0    |    2    |    3     |   1   |
++-----------+---------+--------+--------+---------+----------+-------+
 ```
 
+The generated report contains failure or warning reasons, but it's considered as passed if the fix was successful.
+
 ### Exit Status Logic
 
 `t4sanity` CLI returns the exit code based on the following conditions:

docs/tutorials/sanity.md

@@ -22,12 +22,28 @@ save_json(serialize_dataclass(result), "result.json")
 
 ### How to Add New Checkers
 
+The following diagram shows the logic of the checkers:
+
+```mermaid
+flowchart LR
+    Start --> A{Can skip?}
+    A --> |Yes| B[Skip check and <br/>returns skipped report]
+    A --> |No| C[Perform check]
+    C --> D{Failed and --fix=True?}
+    D --> |Yes| E[Fix issues]
+    E --> F[Return report]
+    D --> |No| F
+```
+
 All checkers must follow:
 
 - Implement a class that inherits from `Checker` class.
 - Its ID must be unique and belong to one of `RuleGroup` enum.
-- Override the `check() -> list[Reason] | None` method to perform the specific check.
 - Register the checker using `CHECKERS.register()` decorator.
+- Override the `check(...) -> list[Reason] | None` method to perform the specific check.
+- [OPTIONAL] The following methods can be overridden if needed:
+  - Override `can_skip(...) -> Maybe[Reason]` method to determine whether the checker can be skipped.
+  - Override `fix(...) -> bool` method to fix the issue if possible.
 
 ```python title="str000.py"
 from __future__ import annotations