feat: add example for starship and shell_space (#320)

prompt/README.md

@@ -3,3 +3,25 @@
 ### Definition
 
 These scripts should be used to draw a custom command prompt in nushell. They can include anything that we think is appropriate for prompts such as `git` commands, `starship`, `oh-my-posh`, etc.
+
+#### starship.nu
+
+File is in [starship](./starship.nu) 
+
+This discribe how to use starship to make a leftprompt, the repo of starship is [here](https://github.com/starship/starship).
+
+This script set the output of starship as leftprompt
+
+![starshipshow](./images/starship.png)
+
+#### shell_space.nu
+
+File is in [shell_space](./shell_space.nu)
+
+Use the function of shells in nu, you can view the fucntion with the command following
+
+```
+help shells
+```
+
+![shell_spaceshow](./images/shell_space.png)

prompt/shell_space.nu

@@ -0,0 +1,21 @@
+# use shells to to show workspaces
+def workspaces [] {
+    shells | each {|item index|
+      if $item.active {
+        $"(ansi green)($index) "
+      } else {
+        $"(ansi blue)($index) " 
+      }
+    }| str collect
+}
+
+def create_right_prompt [] {
+    let time_segment = ([
+        (date now | date format '%r'),
+        " ",
+        (workspaces)
+    ] | str collect)
+    $time_segment
+}
+
+let-env PROMPT_COMMAND_RIGHT = { create_right_prompt }

prompt/starship.nu

@@ -0,0 +1,11 @@
+def create_left_prompt [] {
+    ^starship prompt --cmd-duration $env.CMD_DURATION_MS $'--status=($env.LAST_EXIT_CODE)'
+}
+
+let-env PROMPT_COMMAND = { create_left_prompt }
+
+# avoid same PROMPT_INDICATOR
+let-env PROMPT_INDICATOR = { "" }
+let-env PROMPT_INDICATOR_VI_INSERT = { ": " }
+let-env PROMPT_INDICATOR_VI_NORMAL = { "〉" }
+let-env PROMPT_MULTILINE_INDICATOR = { "::: " }