[doc only] Add today's TWiG

.dictionary

@@ -1,4 +1,4 @@
-personal_ws-1.1 en 219 utf-8
+personal_ws-1.1 en 220 utf-8
 AAR
 AARs
 ABI
@@ -185,6 +185,7 @@ rkv
 rkv's
 runtime
 runtimes
+rustc
 rustup
 schemas
 sdk

docs/user/appendix/twig.md

@@ -44,3 +44,4 @@ They could be release notes, documentation, hopes, dreams, or whatever: so long
 * 2021-01-28: [The Glean Dictionary](https://blog.mozilla.org/data/2021/01/27/this-week-in-glean-the-glean-dictionary/)
 * 2021-02-24: [Boring Monitoring](https://blog.mozilla.org/data/2021/02/24/this-week-in-glean-boring-monitoring/)
 * 2021-04-07: [Publishing Glean.js or “How I configured an npm package that has multiple entry points”](https://blog.mozilla.org/data/2021/04/07/this-week-in-glean-publishing-glean-js/)
+* 2021-04-16: [rustc, iOS and an M1](https://blog.mozilla.org/data/2021/04/16/this-week-in-glean-rustc-ios-and-an-m1/)