Add documentation for decorators (#988)
Add documentation for decorators (#988)

The new file `tutorial/decorators.md` describes the usage of Pyccel's decorators.

Co-authored-by: Yaman Güçlü <d1db2ebdb7379dcf65f6e5d3f2ec1196a5538f9a@gmail.com>
Co-authored-by: EmilyBourne <ebfdddc2dabf525d667480b6ccb2490bf0bb459f@gmail.com>
ratnania/pyccel,ratnania/pyccel