Add docs for using external API with security

[kumaranvpl]

Description

Please include a summary of the change and specify which issue is being addressed. Additionally, provide relevant motivation and context.

Fixes #141

Type of change

Please delete options that are not relevant.

• Documentation (typos, code examples, or any documentation updates)
• Bug fix (a non-breaking change that resolves an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a fix or feature that would disrupt existing functionality)
• This change requires a documentation update

Checklist

• My code adheres to the style guidelines of this project (scripts/lint.sh shows no errors)
• I have conducted a self-review of my own code
• I have made the necessary changes to the documentation
• My changes do not generate any new warnings
• I have added tests to validate the effectiveness of my fix or the functionality of my new feature
• Both new and existing unit tests pass successfully on my local environment by running scripts/test-cov.sh
• I have ensured that static analysis tests are passing by running scripts/static-anaylysis.sh
• I have included code examples to illustrate the modifications

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
...s/docs_src/tutorial/external_rest_apis/security.py	100.00% <100.00%> (ø)

... and 8 files with indirect coverage changes