[DOC] State timezone info in the string wins in: keyword

Author: nobu

test/ruby/test_time.rb

@@ -77,6 +77,7 @@ def test_new_from_string
 
     assert_equal(Time.new(2021), Time.new("2021"))
     assert_equal(Time.new(2021, 12, 25, in: "+09:00"), Time.new("2021-12-25+09:00"))
+    assert_equal(Time.new(2021, 12, 25, in: "+09:00"), Time.new("2021-12-25+09:00", in: "-01:00"))
 
     assert_equal(0.123456r, Time.new("2021-12-25 00:00:00.123456 +09:00").subsec)
     assert_equal(0.123456789r, Time.new("2021-12-25 00:00:00.123456789876 +09:00").subsec)

timev.rb

@@ -380,6 +380,12 @@ def self.at(time, subsec = false, unit = :microsecond, in: nil)
   #   Time.new(in: '-12:00')
   #   # => 2022-08-23 08:49:26.1941467 -1200
   #
+  # Since +in:+ keyword argument just provides the default, so if the
+  # first argument in single string form contains time zone information,
+  # this keyword argument will be silently ignored.
+  #
+  #   Time.new('2000-01-01 00:00:00 +0100', in: '-0500').utc_offset  # => 3600
+  #
   # - +precision+: maximum effective digits in sub-second part, default is 9.
   #   More digits will be truncated, as other operations of \Time.
   #   Ignored unless the first argument is a string.