Fixed some typos & language in pkg/PORTING

pkg/PORTING

@@ -1,10 +1,10 @@
 This directory provides some porting information for libraries and programs to
-use with RIOT (to build an external module). If you like add a package to RIOT
-you need to add directory to this directory with the name of your package. This
-directory should contain at least to files:
+use with RIOT (to build an external module). If you'd like to add a package to 
+RIOT you need to add a directory with the name of your package to this directory.
+Your directory should contain at least two files:
  * patch.txt    - Your patch of the upstream project of the package to make it
                   build with RIOT
  * Makefile     - A Makefile describing how to get the upstream project, apply
                   the patch and how to build the package as a RIOT module.
-                  a rough template for several methods of aquiring a package
-                   is provided in Makefile.git, Makefile.http, and Makefile.svn
+                  A rough template for several methods of acquiring a package
+                  is provided in Makefile.git, Makefile.http, and Makefile.svn