Remove outdated LOCs in README.md

Wikimetrics considerably out-grew the 1500 LOC of Python code, and is
currently more ~5K LOC [1]. So we drop the mentioning of LOC, as
constantly updating is a pain anyways.

[1]
cat $(find wikimetrics | grep '\.py$') | wc -l
5079

Change-Id: I6a51cfe203cda0e1539ac7091033c1c6886cbc77