Doc - Add info on how to update max shards

[AnaelMobilia]

Add information on how to fix "Elasticsearch error: RequestError(400, 'validation_exception', 'Validation Failed: 1: this action would add [1] shards, but this cluster currently has [1000]/[1000] maximum normal shards open;"

[codecov[bot]]

Codecov Report

Base: 59.23% // Head: 59.23% // No change to project coverage :thumbsup:

Coverage data is based on head (e034b7b) compared to base (49f9d75). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #368 +/- ## ======================================= Coverage 59.23% 59.23% ======================================= Files 10 10 Lines 1332 1332 ======================================= Hits 789 789 Misses 543 543 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=domainaware). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=domainaware)

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[AndrewKvalheim]

Maybe add a note about monthly_indexes?

[AnaelMobilia]

@AndrewKvalheim Please feel free to open a pull request adding information about monthly_indexes :-)

Bests regards, Anael

[seanthegeek]

Thanks for all of the documentation improvements. Sorry I have neglected this project for so long.