Update Install.rst

Line 40 of Install.rst, removed additional wording "and is the one where the software is more tested" as it isn't necessary
Line 95 of Install.rst, removed "Take" from "Take special attention..." and replaced with "Pay special attention.." as a standard usage of the term.
Line 104 of Install.rst, changed "doesn't" to "won't" to reduce duplicate word usage in the sentence.