doc: Code wrap default value in README

Author: rtfpessoa

README.md

@@ -151,7 +151,7 @@ The HTML output accepts a Javascript object with configuration. Possible options
 - `diffStyle`: show differences level in each line: `word` or `char`, default is `word`
 - `matching`: matching level: `'lines'` for matching lines, `'words'` for matching lines and words or `'none'`, default
   is `none`
-- `matchWordsThreshold`: similarity threshold for word matching, default is 0.25
+- `matchWordsThreshold`: similarity threshold for word matching, default is `0.25`
 - `matchingMaxComparisons`: perform at most this much comparisons for line matching a block of changes, default is
   `2500`
 - `maxLineSizeInBlockForComparison`: maximum number os characters of the bigger line in a block to apply comparison,