Add release notes for #19644

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: T-Gro

docs/release-notes/.FSharp.Compiler.Service/11.0.100.md

@@ -1,6 +1,7 @@
 ### Fixed
 
 * Fix attributes on return type of unparenthesized tuple methods being silently dropped from IL. ([Issue #462](https://github.com/dotnet/fsharp/issues/462), [PR #19714](https://github.com/dotnet/fsharp/pull/19714))
+* Fix false-positive nullness warning (FS3261) when pattern matching narrows nullness inside seq/list/array comprehensions. ([Issue #19644](https://github.com/dotnet/fsharp/issues/19644), [PR #19743](https://github.com/dotnet/fsharp/pull/19743))
 * Fix internal error FS0073 "Undefined or unsolved type variable" in IlxGen when nested inline SRTP functions with multiple overloads leave unsolved typars in the non-witness codegen path. ([Issue #19709](https://github.com/dotnet/fsharp/issues/19709), [PR #19710](https://github.com/dotnet/fsharp/pull/19710))
 * Fix NRE when calling virtual Object methods on value types through inline SRTP functions. ([Issue #8098](https://github.com/dotnet/fsharp/issues/8098), [PR #19511](https://github.com/dotnet/fsharp/pull/19511))
 * Fix attributes not resolved from opened namespaces in `namespace rec` / `module rec` scopes. ([Issue #7931](https://github.com/dotnet/fsharp/issues/7931), [PR #19502](https://github.com/dotnet/fsharp/pull/19502))