DeflateStream decompression app compat issue (microsoft#563)

* DeflateStream decompression app compat issue

* Addressed review comments, fixed typos, removed remarks

* Addressed additional comments

Author: Ron Petrusha

Documentation/compatibility/deflatestream-uses-native-apis-for-decompression.md

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+## DeflateStream uses native APIs for decompression
+
+### Scope
+Minor
+
+### Version Introduced
+4.7.2
+
+### Source Analyzer Status
+NotPlanned
+
+### Change Description
+
+Starting with the .NET Framework 4.7.2, the implementation of decompression in the `T:System.IO.Compression.DeflateStream` class has changed to use native Windows APIs by default. This results in an average performance improvement of approximately 300%. All .NET applications running on machines with versions of the .NET Framework starting with version 4.7.2 will now use the native implementation. 
+
+This change might result in some differences in behavior, which include:
+
+- Exception messages may be different. However, the type of exception thrown remains the same.
+ 
+- Some special situations, such as not having enough memory to complete an operation, may be handled differently.
+ 
+- [X] Quirked 
+- [ ] Build-time break 
+
+### Recommended Action
+
+If decompression with native APIs has adversely affected the behavior of your app, you can opt out of this feature by adding the `Switch.System.IO.Compression.DoNotUseNativeZipLibraryForDecompression` switch to the `runtime` section of your app.config file and setting it to `true`:
+
+```xml
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+    <runtime>
+       <AppContextSwitchOverrides
+          value="Switch.System.IO.Compression.DoNotUseNativeZipLibraryForDecompression=true" />
+    </runtime>
+</configuration>
+```
+### Affected APIs
+`T:System.IO.Compression.DeflateStream`
+`T:System.IO.Compression.GZipStream`
+
+### Category
+Core
+
+<!--
+    #518398
+-->
+
+