[DOCS] Maximum length for levenshtein algorithm

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.2/static/fuzzystrmatch.html
Description:

While the documenation of the versions 9.5 and 9.6 states a maximum length
of 255 characters for the levenshtein algorithm's input, the documentation
of any previous version states a maximium of 255 bytes. I expect that this
hasn't change, but the documentation of older versions is wrong.