add a zh document: deploy postgis on polardb

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[polardb-bot[bot]]

Hi @digoal ~ Congratulations to your first PR to PolarDB. 🎉

Please make sure that your PR conforms the standard, and has passed all the checks.

We will review your PR as soon as possible.

[polardb-bot[bot]]

Hey @digoal :

Congratulations~ 🎉 Your commit has passed all the checks. Please wait for further manual review.

[polardb-bot[bot]]

Hey @digoal :

Congratulations~ 🎉 Your commit has passed all the checks. Please wait for further manual review.

[polardb-bot[bot]]

Hey @digoal :

Something wrong occuried during the checks of your commit 😟, please check the detail:

⚠️ docs View more details

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