Fix typo

Author: dspinellis

src/ai_cli.7

@@ -93,7 +93,7 @@ section and the format documented in
 
 .SH ENVIRONMENT VARIABLES
 All configuration entries specified through
-.BR ai_cli (5).
+.BR ai_cli (5)
 can be overridden by supplying to a program's
 invocation an environment variable named
 \fCAI_CLI_\fIsection\fC_\fIoption\fR,