chore: Update benchmarking location in contributing docs (#3180)

# What does this PR do?
Small docs change as requested in
#3160 (review)


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## Test Plan
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Author: franciscojavierarceo

docs/source/contributing/index.md

@@ -23,12 +23,7 @@ new_vector_database
 ```{include} ../../../tests/README.md
 ```
 
-## Benchmarking
-
-```{include} ../../../docs/source/distributions/k8s-benchmark/README.md
-```
-
-### Advanced Topics
+## Advanced Topics
 
 For developers who need deeper understanding of the testing system internals:
 
@@ -37,3 +32,8 @@ For developers who need deeper understanding of the testing system internals:
 
 testing/record-replay
 ```
+
+### Benchmarking
+
+```{include} ../../../docs/source/distributions/k8s-benchmark/README.md
+```