_content/blog: fix typo in execution traces 2024 post

Change-Id: Ida1ac5b41924f863f0b443ad874ed6a43730f4f4
Reviewed-on: https://go-review.googlesource.com/c/website/+/571677
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/_content/blog/execution-traces-2024.md b/_content/blog/execution-traces-2024.md
index 0d005b3..c1d3d2c 100644
--- a/_content/blog/execution-traces-2024.md
+++ b/_content/blog/execution-traces-2024.md
@@ -54,7 +54,7 @@
 It turned out that much of the cost of tracing came down to tracebacks.
 Many events produced by the runtime have stack traces attached, which are invaluable to actually
-identifying what goroutines where doing at key moments in their execution.
+identifying what goroutines were doing at key moments in their execution.
 Thanks to work by Felix Geisendörfer and Nick Ripley on optimizing the efficiency of tracebacks,
 the run-time CPU overhead of execution traces has been cut dramatically, down to 1–2% for many