Fixing inconsistent use of RewriteRule in docs and install.php5

It currently doesn't match the .htaccess that comes with a checkout of
silverstripe-installer.

dev/install/install.php5

@@ -1528,7 +1528,7 @@ ErrorDocument 500 /assets/error-500.html
 	
 	RewriteCond %{REQUEST_URI} ^(.*)$
 	RewriteCond %{REQUEST_FILENAME} !-f
-	RewriteRule .* $modulePath/main.php?url=%1&%{QUERY_STRING} [L]
+	RewriteRule .* $modulePath/main.php?url=%1 [QSA]
 </IfModule>
 TEXT;
 

docs/en/reference/execution-pipeline.md

@@ -9,7 +9,7 @@ This page documents all the steps from an URL request to the delivered page.
 Silverstripe uses **[mod_rewrite](http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html)** to deal with page requests.
 So instead of having your normal everyday `index.php` file which tells all, you need to look elsewhere. 
 
-The basic .htaccess file after installing SilverStripe look like this:
+The basic .htaccess file after installing SilverStripe looks like this:
 
 	<file>
 	### SILVERSTRIPE START ###
@@ -23,11 +23,13 @@ The basic .htaccess file after installing SilverStripe look like this:
 	<IfModule mod_rewrite.c>
 	RewriteEngine On
 
-	RewriteCond %{REQUEST_URI} !(\.gif$)|(\.jpg$)|(\.png$)|(\.css$)|(\.js$)
+	RewriteRule ^vendor(/|$) - [F,L,NC]
+	RewriteRule silverstripe-cache(/|$) - [F,L,NC]
+	RewriteRule composer\.(json|lock) - [F,L,NC]
 
 	RewriteCond %{REQUEST_URI} ^(.*)$
 	RewriteCond %{REQUEST_FILENAME} !-f
-	RewriteRule .* framework/main.php?url=%1&%{QUERY_STRING} [L]
+	RewriteRule .* framework/main.php?url=%1 [QSA]
 	</IfModule>
 	### SILVERSTRIPE END ###
 	</file>