Update information regarding Leeuwenhoek

[jonathanbeber]

I couldn't find references to sustain the information that Leeuwenhoek invented the microscope. Indeed his letter to the royal society was a mark in the microbiology area and motivated Hooke to improve the research of microrganisms, but the microscope was already invented and even used, for example, by Hoooke himself to write Micrographia.

This commit changes the information to refer Leeuwenhoek as one the first microscopists and microbiologists, instead of the inventor of the microscope.