Add reference in sites.tex

Thanks to Julia
http://stacks.math.columbia.edu/tag/039Z#comment-1182
http://stacks.math.columbia.edu/tag/039Z#comment-1186
Fix reference in more-algebra.tex
Add missing 'of' in sites-modules.tex

Thanks to Mohamed Hashi
http://stacks.math.columbia.edu/tag/0408#comment-1188
Fixes to dualizing.tex

Thanks to Felipe Zaldivar
http://stacks.math.columbia.edu/tag/08Y1#comment-1189
Fix typo in algebra.tex

Thanks to Lenny Taelman
http://stacks.math.columbia.edu/tag/00NX#comment-1191
Fix statement lemma in algebra.tex

Thanks to Mohamed Hashi
http://stacks.math.columbia.edu/tag/07LV#comment-1192
Fix statement lemma in sites.tex

Thanks to JuanPablo
http://stacks.math.columbia.edu/tag/090K#comment-1193
Fix definition in more-algebra.tex

Thanks to Max
http://stacks.math.columbia.edu/tag/092B#comment-1194