update docs for updating v4 to newest

What version of Invoice Ninja are you running? ie v4.5 / v5
v4.5

Request
Could you please update the paragraph

> To update the app you just need to copy over the latest code. The app tracks the current version in a file called version.txt, if it notices a change it loads /update to run the database migrations.

to

> To update the app you just need to copy over the latest code. _Do not be afraid to overwrite the files, the configuration file for connections such as mysql are stored in the .env file._ The app tracks the current version in a file called version.txt, if it notices a change it loads /update to run the database migrations.

and add...

> If you overwrite files manually and get an error 403, check your .htaccess file and uncomment this line
> RewriteRule ^(.*)$ public/$1 [L]

here


and some context for this request: