Updated README.md with installation steps
Updated README.md with installation steps

On my machine `make pdf` resulted in a lot `make: *** [pdf] Error 43` errors. The causes were missing LaTeX packages.
After installing and updating the packages everything worked smoothly.
tompollard/phd_thesis_markdown,tompollard/phd_thesis_markdown,tompollard/phd_thesis_markdown,dangrie158/email-categorization-thesis