Standardize the use of index files across top-level topics

[bgravenorst]

There is an inconsistency in how index files (index.md) are used across different top-level topics within the documentation. Specifically, some top-level topics contain content within their index.md files, while others do not. This inconsistency can lead to confusion for both users navigating our documentation and contributors maintaining it.

For this issue we may need to decide on a consistant approach first.

[Vtalike]

There is an inconsistency in how index files (index.md) are used across different top-level topics within the documentation. Specifically, some top-level topics contain content within their index.md files, while others do not. This inconsistency can lead to confusion for both users navigating our documentation and contributors maintaining it.

For this issue we may need to decide on a consistant approach first.

[m4sterbunny]

Per the reorg, this is fixed for Stack/
This only partially fixed for Network:
✅ /network/overview
✅ /network/build --> ❌ /network/build/tools
❌ /network/howto
❌ /network/tutorials
There is an instance in Protocol
❌ I did not apply to Protocol/reference as that is a bucket -- is this a valid exception or does it need rethink too?

Final decision needed on the ia OR I can add index page that offers the most popular sibling pages as cards per network/quickstart OR all the sibling pages as cards per network/build