Pangolin installation version specification for cilantro_build.md

[WangYixuan12]

Hi! Thanks for your great documentation! After following cilantro installation instructions, I found git clone from Pangolin does not work. The newest Pangolin cannot be included using Pangolin_INCLUDE_DIRS, as used in cilantro CMakeLists.txt. I found Pangolin v6.0 can work perfectly. Maybe you could specify the version in the documentation.

[WangYixuan12]

Another suggestion: I think now modern cilantro is supported. You may change it in cilandro_build.md

[shaisung]

Another suggestion: I think now modern cilantro is supported. You may change it in cilandro_build.md

Note that as of August 2021, cilantro uses C++17 features:
kzampog/cilantro@02bc240

And hence requires CUDA11.

I just banged my head against that for a few days trying to compile with CUDA10.1...