Documentation: change "&" to "and" in Documentation/applying-patches.txt

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 When patch applies a patch file it attempts to verify the sanity of the

file in different ways.

Checking that the file looks like a valid patch file & checking the code

Checking that the file looks like a valid patch file and checking the code

around the bits being modified matches the context provided in the patch are

just two of the basic sanity checks patch does.