docs/zh_CN: move sparse into dev-tools

../zh_CN/saprse.txt is alone at here, let's move it to ../zh_CN/dev-tools/sparse.rst.
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/0f1182add7afe4e3b42398353a823d1b4dcf5147.1637565886.git.siyanteng@loongson.cnSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/dev-tools/index.rst

@@ -22,13 +22,13 @@ Documentation/translations/zh_CN/dev-tools/testing-overview.rst
    :maxdepth: 2
 
    testing-overview
+   sparse
    gcov
    kasan
 
 Todolist:
 
  - coccinelle
- - sparse
  - kcov
  - ubsan
  - kmemleak