tab indentation comment (#6079)

## Summary

Updated doc comment for `tab_indentation.rs`. Online docs also benefit
from this update.

## Test Plan

Checked docs via
[mkdocs](https://github.com/astral-sh/ruff/blob/389fe13c934fe73679474006412b1eded4a2cad0/CONTRIBUTING.md?plain=1#L267-L296)

crates/ruff/src/rules/pycodestyle/rules/tab_indentation.rs

@@ -5,6 +5,26 @@ use ruff_macros::{derive_message_formats, violation};
 use ruff_python_ast::source_code::Indexer;
 use ruff_python_trivia::{leading_indentation, Line};
 
+/// ## What it does
+/// Checks for indentation that uses tabs.
+///
+/// ## Why is this bad?
+/// According to [PEP 8], spaces are preferred over tabs (unless used to remain
+/// consistent with code that is already indented with tabs).
+///
+/// ## Example
+/// ```python
+/// if True:
+/// a = 1
+/// ```
+///
+/// Use instead:
+/// ```python
+/// if True:
+/// a = 1
+/// ```
+///
+/// [PEP 8]: https://peps.python.org/pep-0008/#tabs-or-spaces
 #[violation]
 pub struct TabIndentation;
 

scripts/check_docs_formatted.py

@@ -55,6 +55,7 @@
  "prohibited-trailing-comma",
  "shebang-leading-whitespace",
  "surrounding-whitespace",
+ "tab-indentation",
  "too-few-spaces-before-inline-comment",
  "trailing-comma-on-bare-tuple",
  "triple-single-quotes",