docs: theme config and list of theme templates (#116)

- Added theme configuration guide in README
- Added some theme templates
- Added list of theme templates in `themes/`

themes/catppuccin-macchiato.toml

@@ -0,0 +1,19 @@
+border = "#c6a0f6"
+accent = "#8bd5ca"
+muted = "#6e738d"
+text = "#cad3f5"
+text_sel = "#cad3f5"
+key = "#c6a0f6"
+match = "#a6da95"
+desc = "#a5adcb"
+desc_sel = "#cad3f5"
+sel_bg = "#5b6078"
+sel_text = "#24273a"
+scroll_info = "#c6a0f6"
+ghost_text = "#5b6078"
+sys = "#363a4f"
+sys_sel = "#f5a97f"
+hist = "#1e2030"
+hist_sel = "#8bd5ca"
+alias = "#363a4f"
+alias_sel = "#c6a0f6"