Add Hietan/Hietan_ZshTheme

- https://github.com/Hietan/Hietan_ZshTheme/issues/1 is closed, add `hietan/hietan` theme

Signed-off-by: Joe Block <jpb@unixorn.net>

README.md

@@ -2062,6 +2062,7 @@ If you're using [Antigen](https://github.com/zsh-users/antigen), you can test th
 - [helb](https://github.com/helb/helb.zshtheme) - Loosely based on Gentoo's old `bash` theme. Includes `git` information, return value of last command, and uses different username color and prompt char for users (`$`) and root (`#`).
 - [hematite](https://github.com/bigdave/hematite) - Minimalist promot that tries to show only the status decorations that are actively useful at a given time.
 - [hex](https://github.com/hectorBrown/hex-zsh) - Heavily based on [bira](https://github.com/ohmyzsh/ohmyzsh/wiki/Themes#bira), and [gruvbox](https://github.com/sbugzu/gruvbox-zsh), which in turn is based on [agnoster](https://gist.github.com/agnoster/3712874). Includes decorators for current directory, `git` status information, active python virtualenv, exit status of the last command run. Requires a Powerline-compatible font.
+- [hietan](https://github.com/Hietan/Hietan_ZshTheme) - Includes decorators for current directory, date & time, `git` status and the exit value of the last command run. Requires a Nerd Font.
 - [hexagon](https://github.com/diogoazevedos/hexagon) - Minimalist ZSH theme based on [geometry](https://github.com/geometry-zsh/geometry).
 - [hfulldate](https://github.com/fusion809/zsh-theme) - Displays time, date, OS (including distro if on Linux), directory and whether running as root.
 - [hhktony](https://github.com/hhktony/hhktony.zsh-theme) - Inspired by robbyrussell theme + ssh connection status prompt.