Bad link for tutorial

[samkho]

README.md says:

Read the excellent CIL tutorial by Zachary Anderson

but the CIL tutorial link:

https://bitbucket.org/zanderso/cil-template/downloads/ciltut.pdf

leads to a page saying:

Repository not found
You may not have access to this repository or it no longer exists in this workspace.

[michael-schwarz]

There's a copy of the tutorial on Westley Weimer's pages at UMichigan https://web.eecs.umich.edu/~weimerw/2011-6610/reading/ciltut.pdf

(Afaik, CIL is no longer being actively maintained (see e.g. the discussion in this PR: #42). There's several forks that see some active development.)