CHANGELOG.md: Add thanks section
Instead of reporting every small PR, have a generalised thanks
section.
### Changed
- [Fix local bash-completion directory path][pr#1809]
-- [Removed duplicate wording in help][pr#1812]
-- [Removed duplicated import of std::env][pr#1817]
- [Handle stray toolchain hashes during install][pr#1801]
- [Update to env_proxy 0.3.1][pr#1819]
- [Improvements to release process around Windows versions][pr#1822]
- [Added CI of CentOS 6 support for rustup-init.sh][pr#1810]
- [FAQ entry about not being able to update rustup on Windows][pr#1813]
+### Thanks
+
+This release was made, in part, thanks to:
+
+* Brian Ericson
+* Onat Mercam
+* Lzu Tao
+* Takuto Ikuta
+* Jason Williams
+* Filip Demski
+* Michael Maclean
+* Daniel Silverstone
+
[pr#1809]: https://github.com/rust-lang/rustup.rs/pull/1809
-[pr#1812]: https://github.com/rust-lang/rustup.rs/pull/1812
-[pr#1817]: https://github.com/rust-lang/rustup.rs/pull/1817
[pr#1801]: https://github.com/rust-lang/rustup.rs/pull/1801
[pr#1819]: https://github.com/rust-lang/rustup.rs/pull/1819
[pr#1822]: https://github.com/rust-lang/rustup.rs/pull/1822
