[docs] Windows: for god

docs/Build.md

@@ -60,7 +60,9 @@ Hit "Configure Project", then wait for CMake to finish configuring (may take a w
 >  - It's recommended to install **[Ninja](https://ninja-build.org/)**
 >  - You must load **Visual C++ development environment**, this can be done by running our convenience script:
 >    - `tools/windows/load-msvc-env.ps1`
->  - You need to add the environment variable `CL` with the `/FS` flag (`set CL=/FS`)  if you're using ccache to speed up build process
+>  - If you're using CCache:
+>    - You need to add the environment variable `CL` with the `/FS` flag (`set CL=/FS`)
+>    - Build may fail cause multiple cl instaces are trying to write to the same file (and Windows can't do it nicely), just hit "Build" again (you may need to do it a few times)
 
 Availables `<GENERATOR>`:
 - MSYS2: `MSYS Makefiles`