Rename README to README.md.
Convert README.md to UTF-8, because it's the 21st century.
Insert various code spans and text emphasis where applicable.

Includes a few UTF-8 substitutes for arrows, ellipsis dots etc.

Plus, I have never seen "e.g." contain a whitespace, so I took the liberty to
remove that example for non-breaking spaces.
Add link to bjoernd's vim-weasel package.
Hinted to the makefile targets, removed duplicate entries