Add validate() in list of executed methods in conan commands documentation

[SpaceIm]

conan install and conan create documentation provide informations about order of execution of ConanFile methods: https://docs.conan.io/en/latest/reference/commands/consumer/install.html https://docs.conan.io/en/latest/reference/commands/creator/create.html

The new method validate() added in 1.32.0 is missing.