docs(README.md): remove obsolete links to portable builds for windows

README.md

@@ -10,8 +10,6 @@ qTox
 * **Windows**:
   - [**64 bit installer**](https://build.tox.chat/view/qtox/job/qTox_pkg_windows_x86-64_stable_release/lastSuccessfulBuild/artifact/setup-qtox.exe)
   - [**32 bit installer**](https://build.tox.chat/view/qtox/job/qTox_pkg_windows_x86_stable_release/lastSuccessfulBuild/artifact/setup-qtox.exe)
-  - [**64 bit portable**](https://build.tox.chat/job/qTox_build_windows_x86-64_release/lastSuccessfulBuild/artifact/qTox_build_windows_x86-64_release.zip)
-  - [**32 bit portable**](https://build.tox.chat/job/qTox_build_windows_x86_release/lastSuccessfulBuild/artifact/qTox_build_windows_x86_release.zip)
 * **Linux**:
   - [**64 bit download**](https://build.tox.chat/view/Clients/job/qTox_build_linux_x86-64_release/lastSuccessfulBuild/artifact/qTox_build_linux_x86-64_release.tar.xz)
   - [**32 bit download**](https://build.tox.chat/view/Clients/job/qTox_build_linux_x86_release/lastSuccessfulBuild/artifact/qTox_build_linux_x86_release.tar.xz)