appveyor example invalid

The example in https://docs.conan.io/en/latest/integrations/ci/appveyor.html is invalid (indentation, cmmd). I am new to appveyor. I guess it should be:

```yml
version: 1.0.{build}
platform:
- x64

install:
- cmd: echo "Downloading conan..."
- cmd: set PATH=%PATH%;%PYTHON%/Scripts/
- cmd: pip.exe install conan
- cmd: conan user # Create the conan data directory
- cmd: conan --version

build_script:
- cmd: mkdir build
- cmd: conan install . -o gtest:shared=True
- cmd: cd build
- cmd: cmake ../ -DBUILD_TEST=TRUE -G "Visual Studio 14 2015 Win64"
- cmd: cmake --build . --config Release

test_script:
- cmd: cd bin
- cmd: encryption_test.exe
```

Open the AppVeyor example at https://docs.conan.io/en/latest/integrations/ci/appveyor.html and compare its YAML indentation and command syntax with the proposed example. Done means the documented configuration is valid for AppVeyor and accurately reflects the shown Conan, CMake, build, and test commands.

Written by the indexing model from the issue text.