Improve documentation for core is-installed command (#237)

* improve documentation for core is-installed command

* Regenerate README

* Fix PHPCS issues

---------

Co-authored-by: Daniel Bachhuber <[email protected]>

Author: petertwise

README.md

@@ -207,16 +207,23 @@ to communicate whether WordPress is installed.
 
 **EXAMPLES**
 
-    # Check whether WordPress is installed; exit status 0 if installed, otherwise 1
-    $ wp core is-installed
-    $ echo $?
-    1
+    # Bash script for checking if WordPress is not installed
 
-    # Bash script for checking whether WordPress is installed or not
-    if ! wp core is-installed; then
+    if ! wp core is-installed 2>/dev/null; then
+        # WP is not installed. Let's try installing it.
         wp core install
     fi
 
+    # Bash script for checking if WordPress is installed, with fallback
+
+    if wp core is-installed 2>/dev/null; then
+        # WP is installed. Let's do some things we should only do in a confirmed WP environment.
+        wp core verify-checksums
+    else
+        # Fallback if WP is not installed.
+        echo 'Hey Friend, you are in the wrong spot. Move in to your WordPress directory and try again.'
+    fi
+
 
 
 ### wp core multisite-convert

src/Core_Command.php

@@ -348,15 +348,23 @@ function () use ( $temp ) {
 	 *
 	 * ## EXAMPLES
 	 *
-	 *     # Check whether WordPress is installed; exit status 0 if installed, otherwise 1
-	 *     $ wp core is-installed
-	 *     $ echo $?
-	 *     1
+	 *     # Bash script for checking if WordPress is not installed
 	 *
-	 *     # Bash script for checking whether WordPress is installed or not
-	 *     if ! wp core is-installed; then
+	 *     if ! wp core is-installed 2>/dev/null; then
+	 *         # WP is not installed. Let's try installing it.
 	 *         wp core install
 	 *     fi
+	 *
+	 *     # Bash script for checking if WordPress is installed, with fallback
+	 *
+	 *     if wp core is-installed 2>/dev/null; then
+	 *         # WP is installed. Let's do some things we should only do in a confirmed WP environment.
+	 *         wp core verify-checksums
+	 *     else
+	 *         # Fallback if WP is not installed.
+	 *         echo 'Hey Friend, you are in the wrong spot. Move in to your WordPress directory and try again.'
+	 *     fi
+
 	 *
 	 * @subcommand is-installed
 	 */