Add OmniSharp#1854 to changelog

Author: JoeRobich

CHANGELOG.md

@@ -10,6 +10,7 @@ All changes to the project will be documented in this file.
 * Do not use Visual Studio MSBuild if it doesn't have .NET SDK resolver ([#1842](https://github.com/OmniSharp/omnisharp-roslyn/issues/1842), [#1730](https://github.com/OmniSharp/omnisharp-roslyn/issues/1730), PR: [#1845](https://github.com/OmniSharp/omnisharp-roslyn/pull/1845))
 * Allow client to specify symbol filter for FindSymbols Endpoint. (PR: [#1823](https://github.com/OmniSharp/omnisharp-roslyn/pull/1823))
 * Exclude additive classifications from "/highlight" requests ([#1576](https://github.com/OmniSharp/omnisharp-roslyn/issues/1576), PR: [#1726](https://github.com/OmniSharp/omnisharp-roslyn/pull/1726))
+* Upgraded to Mono 6.10.0.105, msbuild 16.6 and added missing targets (PR: [#1854](https://github.com/OmniSharp/omnisharp-roslyn/pull/1854))
 
 ## [1.35.3] - 2020-06-11
 * Added LSP handler for `textDocument/codeAction` request. (PR: [#1795](https://github.com/OmniSharp/omnisharp-roslyn/pull/1795))