[AirInv][Doc] Fixed the Makefile for the manual page generation.
[AirInv][Doc] Fixed the Makefile for the manual page generation.

airsim/airinv,airsim/airinv,airsim/airinv,jwakely/airinv,airsim/airinv,jwakely/airinv,airsim/airinv,jwakely/airinv,airsim/airinv,jwakely/airinv,jwakely/airinv,jwakely/airinv,jwakely/airinv,jwakely/airinv,jwakely/airinv,airsim/airinv,airsim/airinv,airsim/airinv