Update ServicesExtensions.cs

[pingvin1308]

replace string format by index with names

it can be useful for log indexing systems that tries to index values that services passes into the string.

[mgravell]

Fair enough; found the docs: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-7.0#log-message-template - checks out and makes sense

[mgravell]

can you update /docs/releasenotes.md too, please? see existing content for format - this would be in the "unreleased" section currently

[mgravell]

merging, thanks