readme: documented arbitrary precision floats

README.md

@@ -10,10 +10,12 @@ prompt. Work in progress. Very incapable right now.
 The idea behind `bc` is to display partial results to the right of the
 cursor in yellow while we type. A little example can be found in the video
 above. Minor syntactic cleanups have been developed as well (e.g. no `local`
-keyword). We have infinite precision integers and double precision floats.
+keyword). We have infinite precision integers and 90 decimal mantissa precision
+floats.
 
 ## TODO
 
 - A good readline copy (haskeline is sadly out of the question for this project)
 - Comment parsing
 - Closures that can modify the parent environment (but do away with the `local` keyword).
+- Better arbitrary precision floats