README: Document release announcements.
README: Document release announcements.

Thanks to tibbs@fedora for setting up anitya.

zsh-users/zsh-syntax-highlighting,stuha/wbr-zsh,P71/zsh-syntax-highlighting,joshuarubin/dotfiles,P71/zsh-syntax-highlighting,x-way/zsh-syntax-highlighting,zsh-users/zsh-syntax-highlighting,joshuarubin/dotfiles,psprint/zsh-syntax-highlighting,danielshahaf/zsh-syntax-highlighting,x-way/zsh-syntax-highlighting,psprint/zsh-syntax-highlighting,danielshahaf/zsh-syntax-highlighting-debian,danielshahaf/zsh-syntax-highlighting-debian,danielshahaf/zsh-syntax-highlighting,phy1729/zsh-syntax-highlighting,m0vie/zsh-syntax-highlighting,joshuarubin/dotfiles,m0vie/zsh-syntax-highlighting,joshuarubin/dotfiles,phy1729/zsh-syntax-highlighting