docs: Update install instructions to reflect hugo.exe filename change
docs: Update install instructions to reflect hugo.exe filename change

The install tutorial instructed users to rename the *.exe file to
hugo.exe because it used to have a big long name.
In Hugo 0.16 the file is already named hugo.exe, so the tutorial
made no sense on that point. Edited out those instructions.

bogem/hugo,gohugoio/hugo,gohugoio/hugo,mdhender/hugo,fedelibre/hugo,tubo028/hugo,gohugoio/hugo,mayah/hugo,abourget/hugo,mdhender/hugo,abourget/hugo,fedelibre/hugo,tischda/hugo,ffrizzo/hugo,MarkDBlackwell/hugo,fedelibre/hugo,Zenithar/hugo,tischda/hugo,mitchchn/hugo,mdhender/hugo,melo/hugo,tubo028/hugo,ffrizzo/hugo,melo/hugo,bogem/hugo,mitchchn/hugo,Zenithar/hugo,mayah/hugo,anthonyfok/hugo,MarkDBlackwell/hugo,anthonyfok/hugo,digitalcraftsman/hugo,anthonyfok/hugo,fedelibre/hugo,jygastaud/hugo,mdhender/hugo,jygastaud/hugo,digitalcraftsman/hugo