Fix dependency in documentation generation
Fix dependency in documentation generation

Make .NET documentation depend on "main" documentation. Since both
depend on erasing the old documentation directory first, and the .NET
documentation lives in a subdirectory, this both ensures that the .NET
documentation isn't the only documentation generated, and fixes an issue
where the .NET documentation generation could fail if built first
because the parent output directory doesn't exist.

adeschamps/lcm,adeschamps/lcm,bluesquall/lcm,lcm-proj/lcm,lcm-proj/lcm,lcm-proj/lcm,adeschamps/lcm,bluesquall/lcm,adeschamps/lcm,bluesquall/lcm,lcm-proj/lcm,bluesquall/lcm,lcm-proj/lcm,adeschamps/lcm,lcm-proj/lcm,adeschamps/lcm,bluesquall/lcm,lcm-proj/lcm,adeschamps/lcm,lcm-proj/lcm,adeschamps/lcm,bluesquall/lcm,bluesquall/lcm