build: align minimum build dependencies with ndn-cxx
* Recommend boost >= 1.65.1 and gcc >= 7.4.0
* Require clang >= 4.0, or Xcode >= 9.0 on macOS
* Silence an ABI-related diagnostic message from gcc on armv7
* Fix redundant-tags warning with gcc 10
* Add CentOS-specific instructions to docs/INSTALL.rst
* Add Xcode 11.5 to Travis CI
Refs: #5087, #5106
Change-Id: I70746729a132ecb07d4788934385bb403039dba9
diff --git a/README.md b/README.md
index e603989..0a4a74a 100644
--- a/README.md
+++ b/README.md
@@ -44,11 +44,12 @@
since broader community support is key for NDN to succeed as a new Internet architecture.
If you are new to the NDN software community, please read [`README-dev.md`](README-dev.md)
-and the [Contributor's Guide](CONTRIBUTING.md) to get started.
+and the [Contributor's Guide](https://github.com/named-data/.github/blob/master/CONTRIBUTING.md)
+to get started.
## License
-NFD is an open and free software package licensed under the GPL version 3 and is the
-centerpiece of our committement to making NDN's core technology open and free to all
-Internet users and developers. For more information about the licensing details and
-limitations, refer to [`COPYING.md`](COPYING.md).
+NFD is a free and open-source software package licensed under the GPL version 3 and
+is the centerpiece of our committement to making NDN's core technology free and open
+to all Internet users and developers. For more information about licensing, refer to
+[`COPYING.md`](COPYING.md).