[Entry] C++ unordered map: rehash()

[codecademy-docs]

Reason/inspiration (optional)

We would like a new entry on the term rehash() under unordered_map in C++. The entry should be in content/cpp/concepts/unordered-map/terms/rehash/rehash.md

The entry should include the following:

• A description of the term
• A ##Syntax section that includes the syntax of the method and its details
• An ##Example section that show an example of the current entry.
• An ## Codebyte section that have a compilable code inside it showing the current entry in use. Use ```codebyte/cpp to add compilable code.

Please refer to the term entry template, content standards and markdown style guide when working on the PR for this issue.

Entry Type (select all that apply)

New Term for Existing Concept Entry

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[dancikmad]

I can take this issue

[mamtawardhani]

Hey @dancikmad You’re assigned 🎉 In addition to the documents linked in the description, please also look at the Contribution Guide. After creating a PR, the maintainer(s) (with the collaborator label) will add comments/suggestions to address any revisions before approval.