[MINOR][DOC] Use standard quotes instead of "curly quote" marks from Mac in structured streaming programming guides
[MINOR][DOC] Use standard quotes instead of "curly quote" marks from Mac in structured streaming programming guides

This PR fixes curly quotes (`“` and `”` ) to standard quotes (`"`).

This will be a actual problem when users copy and paste the examples. This would not work.

This seems only happening in `structured-streaming-programming-guide.md`.

Manually built.

This will change some examples to be correctly marked down as below:

![2016-08-23 3 24 13](https://cloud.githubusercontent.com/assets/6477701/17882878/2a38332e-694a-11e6-8e84-76bdb89151e0.png)

to

![2016-08-23 3 26 06](https://cloud.githubusercontent.com/assets/6477701/17882888/376eaa28-694a-11e6-8b88-32ea83997037.png)

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #14770 from HyukjinKwon/minor-quotes.

(cherry picked from commit 588559911de94bbe0932526ee1e1dd36a581a423)
Signed-off-by: Sean Owen <291c18f3fb7528c712d9098b0e50a515ea0b91d5@cloudera.com>

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