1: In the SYNOPSIS section, the second argument is referred to as "url". The DESCRIPTION section refers to it alternately as "the given input string" and the "input url".
As it is reasonable to use curl_easy_escape on strings that are not URLs (though they'll probably end up as part of one), I suggest replacing the "url" label with "str" or something like that.

2: It refers to RFC 2396. Should that refer to a more recent RFC?