Refactor documentation structure and add new specifications

- Updated MSH documentation to reflect changes in material, wear, and texture specifications.
- Introduced new `render.md` file detailing the render pipeline process.
- Removed outdated sections from `runtime-pipeline.md` and redirected to `render.md`.
- Added detailed specifications for `Texm` texture format and `WEAR` wear table.
- Updated navigation in `mkdocs.yml` to align with new documentation structure.

crates/msh-core/README.md

@@ -0,0 +1,14 @@
+# msh-core
+
+Парсер core-части формата `MSH`.
+
+Покрывает:
+
+- `Res1`, `Res2`, `Res3`, `Res6`, `Res13` (обязательные);
+- `Res4`, `Res5`, `Res10` (опциональные);
+- slot lookup по `node/lod/group`.
+
+Тесты:
+
+- прогон по всем `.msh` в `testdata`;
+- синтетическая минимальная модель.