Inconsistent capitalization in plot_hdi docstring

[canyon289]

Describe the bug
Docs have inconsistent capitalization

To Reproduce
https://arviz-devs.github.io/arviz/generated/arviz.plot_hdi.html#arviz.plot_hdi

Expected behavior
Consistency across arg docstrings

[neha-shah99]

Hey, I'm new to Open Source and would like to contribute and work on this issue. How can I help?

[OriolAbril]

Hi @neha-shah99, welcome! You have already done the first step which is to indicate what you plan to work on, this way we can prevent two people working on the same issue.

Roughly speaking the steps are: creating a fork of the project, edit the fork and submit a pull request to merge the changes to the main repository. We have a contributing guide which details every step and common commands needed for these steps. If you still have doubts or have suggestions on how to improve it do not hesitate to ask either here or in gitter