update UNIX 03

Author: Vladimir Kotal

intro.tex

@@ -66,7 +66,7 @@
 \item For the API, we will follow the \emph{Single UNIX Specification,
 version~4} (SUSv4). Systems that submit to the Open Group for certification and
 pass conformance tests are termed to be compliant with the UNIX standard
-UNIX~V7.  Some versions of Solaris, AIX, HP-UX a macOS on selected architectures
+UNIX~V7.  Some versions of AIX, HP-UX and macOS on selected architectures
 are compliant with the previous version SUSv3
 (\url{http://www.opengroup.org/openbrand/register/xy.htm}).
 \item The specific source code examples linked from this material are usually