GWP-ASan: Add a link to in-depth blog post

Add a link to an in-depth discussion of GWP-ASan and clarify some
wording.

Change-Id: I3276f12a55e0bbf0ee59fcfdf446f1829e7fd5f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1906930
Auto-Submit: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716015}

docs/gwp_asan.md

@@ -8,6 +8,8 @@ the error.
 It is also known by its recursive backronym, GWP-ASan Will Provide Allocation
 Sanity.
 
+To read a more in-depth explanation of GWP-ASan see [this post](https://sites.google.com/a/chromium.org/dev/Home/chromium-security/articles/gwp-asan).
+
 ## Allocator
 
 The GuardedPageAllocator returns allocations on pages buffered on both sides by
@@ -65,8 +67,8 @@ catch newly introduced bugs, and for specific processes depending on the
 particular allocator.
 
 A [hotlist of bugs discovered by by GWP-ASan](https://bugs.chromium.org/p/chromium/issues/list?can=1&q=Hotlist%3DGWP-ASan)
-exists, though GWP-ASan crashes are filed without external visibility by
-default.
+exists, though GWP-ASan crashes are filed Bug-Security, e.g. without external
+visibility, by default.
 
 ## Limitations