[Doc] Clarify behavior of FileAccess.get_line

[AThousandShips]

Specifies that the line excludes any newline or carriage return characters.

See here for the implementation:

godot/core/io/file_access.cpp

Lines 388 to 393 in 658e97c

	if (c == '\n' || c == '\0') {
	line.push_back(0);
	return String::utf8(line.get_data());
	} else if (c != '\r') {
	line.push_back(c);
	}

• Closes: get-line function from FileAccess not specifying if '\n' and '\r' are included or not [4.2.1] godot-docs#9237

[akien-mga]

Thanks!

[AThousandShips]

Thank you!