Add unmaintained crate informational advisory: term

The author of `term`, @Stebalien, has opened the following GitHub issue
looking for a new maintainer:

Stebalien/term#93

Ideally we can help find one by increasing visibility on this issue.
Otherwise this advisory includes a list of possible alternatives.

crates/term/RUSTSEC-0000-0000.toml

@@ -0,0 +1,18 @@
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "term"
+title = "term is looking for a new maintainer"
+informational = "unmaintained"
+date = "2018-11-19"
+url = "https://github.com/Stebalien/term/issues/93"
+description = """
+The author of the `term` crate does not have time to maintain it and is looking
+for a new maintainer.
+
+Some maintained alternatives you can potentially switch to instead, depending
+on your needs:
+
+- [`crossterm`](https://github.com/crossterm-rs/crossterm)
+- [`termcolor`](https://crates.io/crates/termcolor)
+- [`yansi`](https://crates.io/crates/yansi)
+"""