fix plot's aspect ratio to fit all labels

[monodera]

@wanqqq31 I found that the completion rate plots cannot show labels when more than ~5 priorities are in the target list. I made a quick fix (you can see the screenshot in the "File changed" section). Do you mind if this change is merged? I think you have some thoughts when you made the original plots.

[wanqqq31]

Thanks for the revision. I personally do not like to extend the height of plots that much.. I made some revisions to separate the legend into two columns. Now I think all P0-9 label can be seen. But please let me know you have any concerns.

[monodera]

Thanks! I didn't know about these options for the legend configuration. I further made micro-adjustments.

• legend_columns is 1 if the number of priorities is less than 6.
• put a small space between the plot and legend to avoid overlapping with axis labels.

The screenshot in the document is also updated.

[monodera]

[wanqqq31]

Thanks! It looks good.