Resolve "Documentation update about maximum compressed size"

Closes #2 (closed)

README.md

@@ -160,6 +160,14 @@ decoding.
 Encoded data will be written to the buffer submitted with
 `next_out`. The length of the compressed data is `total_out`.
 
+In rare cases, like for random data, `total_out` can be larger than
+the size of the input data `total_in`. The following should hold true
+even for pathological cases.
+
+```
+total_out <= total_in * 67 / 64 + 256
+```
+
 See libaec.h for a detailed description of all relevant structure
 members and constants.