Fix wrong parameter name in Time.diff_for_humans docstring (#1007)

The docstring documented ":param dt: The time to subtract from", but the
parameter is named "other" and the method compares rather than subtracts.
Both the name and the description were copied from Time.diff just above,
which does take a "dt" argument. Time.diff_for_humans(dt=...) raises
TypeError.

Date.diff_for_humans, which has the identical signature, already documents
":param other: The date to compare to (defaults to today)". This mirrors
that wording.


Claude-Session: https://claude.ai/code/session_01NbQSLKhdfSRcBeGWhaaV6T

Co-authored-by: Geonseok Lee <16929288+hxperl@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: hxperl

src/pendulum/time.py

@@ -247,7 +247,7 @@ def diff_for_humans(
         """
         Get the difference in a human readable format in the current locale.
 
-        :param dt: The time to subtract from
+        :param other: The time to compare to (defaults to now)
         :param absolute: removes time difference modifiers ago, after, etc
         :param locale: The locale to use for localization
         """