Reword command_exists_or_die example, for clarity

Author: joelparkerhenderson

README.md

@@ -196,8 +196,8 @@ Ensure a command exists, otherwise die with a help message.
 command_exists_or_die grep
 => true
 
-command_exists_or_die curl
-STDERR=> Command needed: curl
+command_exists_or_die loremipsum
+STDERR=> Command needed: loremipsum
 => exit 1
 ```
 

posix-shell-script-kit

@@ -613,8 +613,8 @@ command_exists() {
 # command_exists_or_die grep
 # => true
 #
-# command_exists_or_die curl
-# STDERR=> Command needed: curl
+# command_exists_or_die loremipsum
+# STDERR=> Command needed: loremipsum
 # => exit 1
 # ```
 command_exists_or_die() {