doc/next: add release note for work package pattern

For #71294
Fixes #50745

Change-Id: Iff05e98ac860a1764d4c59572f9abc3ae8d9c5fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/658495
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: matloob

doc/next/3-tools.md

@@ -10,6 +10,12 @@ These new error reports may be disabled by setting
 `ASAN_OPTIONS=detect_leaks=0` in the environment when running the
 program.
 
+<!-- go.dev/issue/71294 -->
+
+The new `work` package pattern matches all packages in the work (formerly called main)
+modules: either the single work module in module mode or the set of workspace modules
+in workspace mode.
+
 <!-- go.dev/issue/65847 -->
 
 When the go command updates the `go` line in a `go.mod` or `go.work` file,