shells/zsh-fast-syntax-highlighting: Optimized and extended zsh-syntax-highlighting

Zsh-fast-syntax-highlighting enables highlighting of commands whilst they
are typed at an interactive zsh prompt. This helps in reviewing
commands before running them, particularly in catching syntax errors.
Compared to zsh-syntax-highlighting, this package is more optimized
and feature-rich.

WWW: https://github.com/zdharma-continuum/fast-syntax-highlighting

shells/Makefile

@@ -72,6 +72,7 @@
     SUBDIR += zsh-antigen
     SUBDIR += zsh-autosuggestions
     SUBDIR += zsh-completions
+    SUBDIR += zsh-fast-syntax-highlighting
     SUBDIR += zsh-navigation-tools
     SUBDIR += zsh-syntax-highlighting