ov_eval documentation typo

[AZdet]

Thanks for your great work! While using the ov_eval tool, I found two typos in the documentation page.

1. In transformation section, rosrun ov_eval format_convert folder/path/ should be rosrun ov_eval format_converter folder/path/ instead, as the executable name is format_converter.
2. In plot trajectory section, the order of the order of the gt file and prediction files are flipped in the command template and example command

rosrun ov_eval plot_trajectories <align_mode> <file_gt.txt> ... <file_est9.txt>
rosrun ov_eval plot_trajectories posyaw 1565371553_estimate.txt truths/V1_01_easy.txt

From the code, the command template order is correct (i.e. gt should be the first file).

I'd appreciate it if you could look into them and confirm these are indeed typos. Since the docs folder is not source controlled, I guess it is better to leave them for you to fix (if ever needed), but I am happy to help.