Add note about commands for defines and includes.
Merge topic 'update-buildsystem-docs' into next

4bb7615d Add note about commands for defines and includes.
Help: Mark up the buildsystem commands documentation

Cross-link to the cmake-buildsystem manual.
Help: Document relation of properties to the rest of the buildsystem.
Help: Use ``True`` and ``False`` for IMPORTED values.

Only the first letter is capitalized. It is marked up.
Help: Adjust the QtAutogen properties to the common style.

Link to the cmake-qt manual.
Merge topic 'update-buildsystem-docs' into next

d1730c3a Help: Adjust the QtAutogen properties to the common style.
abba898c Help: Use ``True`` and ``False`` for IMPORTED values.
9135a4d7 Help: Document relation of properties to the rest of the buildsystem.
74a9ebf9 Help: Mark up the buildsystem commands documentation