Fix typo in custom_block.md: change src/config/blocks.ts to src/index.js

[anushka-codes1]

Fixes #914

This PR corrects a typo in the Volto custom block documentation. The configuration file reference has been updated from src/config/blocks.ts to src/index.js to accurately reflect where the block configuration should be added.

Changes

• Updated line 384 in docs/volto-customization/custom_block.md to reference the correct file (src/index.js instead of src/config/blocks.ts)

I, Anushka Mukherjee, agree to have this contribution published under Creative Commons 4.0 International License (CC BY 4.0), with attribution to the Plone Foundation.

Thank you to @adnus for reporting this issue!

---

📚 Documentation preview 📚: https://plone-training--987.org.readthedocs.build/

[stevepiercy]

@anushka-codes1 we need your permission to publish your work. If you agree, then please edit the description of your pull request to include the following statement:

I, [full name], agree to have this contribution published under Creative Commons 4.0 International License (CC BY 4.0), with attribution to the Plone Foundation.

Details: https://training.plone.org/contributing/

Thank you!

[anushka-codes1]

@stevepiercy Updated the comment! Thank you :)

[stevepiercy]

@anushka-codes1 thank you!