build: switch source archive to xz compression

Mention gerrit in the README

Change-Id: I468cedde1a15f760aef00ac2995dd5f73728b89e
diff --git a/README.md b/README.md
index e8074fb..006dbe2 100644
--- a/README.md
+++ b/README.md
@@ -36,11 +36,11 @@
     ./waf
     sudo ./waf install
 
-To build on memory constrained platform, please use `./waf -j1` instead of `./waf`. The
-command will disable parallel compilation.
+To build on memory constrained systems, please use `./waf -j1` instead of `./waf`. This
+will disable parallel compilation.
 
 If configured with tests (`./waf configure --with-tests`), the above commands will also
-generate unit tests that can be run with `./build/unit-tests`.
+build a suite of unit tests that can be run with `./build/unit-tests`.
 
 ## Reporting bugs
 
@@ -49,8 +49,8 @@
 
 ## Contributing
 
-We greatly appreciate contributions to the ChronoSync code base, provided that they are
-licensed under the GNU GPL version 3 or a compatible license.
+Contributions to ChronoSync are greatly appreciated and can be made through our
+[Gerrit code review site](https://gerrit.named-data.net/).
 If you are new to the NDN software community, please read our [Contributor's Guide](
 https://github.com/named-data/.github/blob/main/CONTRIBUTING.md) to get started.