ci: added a spell check workflow for ALLOYDB.md

[twishabansal]

https://github.com/rojopolis/spellcheck-github-actions/tree/v0 is used as the spell checker workflow since it is very popular and actively maintained.

Adding spell check workflows requires us to create a dictionary of technical words so as to recognise them and not cause failures.

Right now, spell check is only configured for the AlloyDB.md file since the file is packaged for use with Gemini CLI. Spell checks for other markdown files will be added separately.

[averikitsch]

This looks config heavy. I'm curious if we enable the Gemini CLI bot if we could get this for free.

[twishabansal]

This looks config heavy. I'm curious if we enable the Gemini CLI bot if we could get this for free.

Could you enable the Gemini Code Assist Bot for code reviews? This allows us to customize behaviour too.

We could write a styleguide and put emphasis on spelling correctness.

[averikitsch]

This looks config heavy. I'm curious if we enable the Gemini CLI bot if we could get this for free.

Could you enable the Gemini Code Assist Bot for code reviews? This allows us to customize behaviour too.

We could write a styleguide and put emphasis on spelling correctness.

Let test this in the genai-toolbox repo first and see if we need to roll it out here.