sed is looking for a maintainer. If you're interested, please take a look at this general information about GNU packages and being a GNU maintainer, and then email maintainers@gnu.org with a bit about your background and particular interest in this package. Thanks.
sed (stream editor) isn't an interactive text editor. Instead, it is used to filter text, i.e., it takes text input, performs some operation (or set of operations) on it, and outputs the modified text. sed is typically used for extracting part of a file using pattern matching or substituting multiple occurrences of a string within a file.
Online documentation is available.