ENH: Add the ability to have a separate title for each subplot when plotting
 - [] tests added / passed
 - [] passes ``git diff upstream/master | flake8 --diff``
 - [] whatsnew entry

## [Current coverage](https://codecov.io/gh/pandas-dev/pandas/pull/14753?src=pr) is 85.26% (diff: 0.00%)
> Merging [#14753](https://codecov.io/gh/pandas-dev/pandas/pull/14753?src=pr) into [master](https://codecov.io/gh/pandas-dev/pandas/branch/master?src=pr) will decrease coverage by **0.01%**

```diff
@@             master     #14753   diff @@
==========================================
  Files           144        144          
  Lines         50968      50977     +9   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43466      43467     +1   
- Misses         7502       7510     +8   
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [3ac41ab...59ab880](https://codecov.io/gh/pandas-dev/pandas/compare/3ac41ab2d7ae446fa04f47ec911003cd722dbd65...59ab880d3de2e52eff5711af4f13a1151d40eb9c?src=pr) Thx for the PR. can u add tests and release note? Also, pls link the original issue if we have. I did my best at adding a test and release note. I didn't see an original issue that this addresses. It's just something I have on my local that I wanted to contribute. Is there anything else I need to do for this change to get pulled in? @TomAugspurger pls have a look when you have a time. Great thanks. +1 for merge when travis passes. Just ping us if you notice that it's green before we do All green :) Huh. I assume there is something funny going on since I didn't change any actual code. Is there a way to restart the checks? Ah! I figured it out. I had a linting error (I'll start doing lint before committing oops!) All green now! Anything else to change? If not, thanks for all the help everyone! I had fun. This was my first pull request but it certainly won't be the last :). @bmagnusson Thanks! Looking forward to more PRs :-)