Update Readme

Added some information about the build process.

Author: Martin Köditz

README.md

@@ -4,10 +4,11 @@
 
 ### Build the driver on Linux
 First of all, we have to meet some requirements. This means we need to install the `phpize` command. The `phpize` command is used to prepare the build environment for a PHP extension.
-Install the `phpize` command. This is usually done by installing the `php7-devel` package using the system's package manager.
-For OpenSuse use
+Install the `phpize` command. This is usually done by installing the `php7-devel` package using the system's package manager. Also install the fbclient library and developer packages.
+
+For OpenSuse 15.1 use
 ```
-$ zypper in php7-devel
+$ zypper in php7-devel libfbclient2 libfbclient-devel
 ```
 
 Now make sure you provide the fbclient.so and the header files (ibase.h). These are needed to compile. You can specify the include path for the ibase.h file with CPPFLAGS as you can see in the following listing.
@@ -24,3 +25,6 @@ $ Build complete.
 $ Don't forget to run 'make test'.
 ```
 You can find the `interbase.so` file in directory `php-firebird/modules`. Copy the file to your php extension dir and restart your webserver.
+
+## Clean up your working directory
+After you've created the binary data, many temporary files will be created in your working directory. These can be removed with the command `phpize --clean`. Then you have a tidy directory again.