change top_opt documentation structure

02_Presentation/top_opt/hca/algo.png

02_Presentation/top_opt/hca/connection.png

02_Presentation/top_opt/hca/hca_strut.gif

02_Presentation/top_opt/hca/load_1.gif

02_Presentation/top_opt/hca/load_2.gif

02_Presentation/top_opt/hca/load_3.gif

02_Presentation/top_opt/hca/load_4.gif

02_Presentation/top_opt/hca/neigh.png

02_Presentation/top_opt/hca/opt.png

02_Presentation/top_opt/hca/res_1.png

02_Presentation/top_opt/search.md

02_Presentation/top_opt/top_opt/concurrent.md

02_Presentation/top_opt/top_opt/microstructure.md

02_Presentation/top_opt/top_opt/multimaterial.md

02_Presentation/top_opt/top_opt/online.md

02_Presentation/top_opt/top_opt/reg.md

README.md