Link to more stages issues

This includes stage 4 issues and closed issues. Since there aren't too many, it seems worth biasing toward showing the historical record, instead of preserving space for only the active proposals.

Author: domenic

Stages.md

@@ -1,6 +1,6 @@
 # WHATWG Stages
 
-**See [all features using the Stages process](https://github.com/search?q=org%3Awhatwg+is%3Aopen+label%3A%22stage%3A+1%22%2C%22stage%3A+2%22%2C%22stage%3A+3%22&type=issues) and their current states.**
+**See [all features using the Stages process](https://github.com/search?q=org%3Awhatwg+label%3A%22stage%3A+1%22%2C%22stage%3A+2%22%2C%22stage%3A+3%22%2C%22stage%3A+4%22&type=issues) and their current states.**
 
 The WHATWG's approach to "documenting reality" is ideal for nailing down [fundamental parts of the platform](https://spec.whatwg.org/) and improving interoperability and developer satisfaction. It can sometimes be daunting for new [Contributors](./IPR%20Policy.md#contributor), who don't know how to reliably get implementer feedback or editor time commitment. The WHATWG Stages process is an optional, opt-in process that both new and established [Contributors](./IPR%20Policy.md#contributor) can use if they want to get more formal signals on support for their [Contribution](./IPR%20Policy.md#21-contribution). This tool is generally used for medium-to-large [Contributions](./IPR%20Policy.md#21-contribution); it's not expected to be used for each [Contribution](./IPR%20Policy.md#21-contribution).