rules to insights edits

Author: Mikejo5000

docs/profiling/perf-rules-string-concatenation.md renamed to docs/profiling/perf-insights-string-concatenation.md

@@ -1,5 +1,5 @@
 ---
-title: Performance tips for string concatenations
+title: Performance insights for string concatenations
 description: Learn how to improve performance for string concatenations.
 ms.date: 7/20/2022
 ms.topic: reference
@@ -17,7 +17,7 @@ ms.workload:
 
 Calls to System.String.Concat are a significant proportion of the profiling data. Consider using the <xref:System.Text.StringBuilder> class to construct strings from multiple segments.
 
-## Rule description
+## Insight description
 
 A <xref:System.String> object is immutable. Therefore, any modification to the string creates a new string object and the garbage collection of the original. This behavior is the same whether you call String.Concat explicitly or use the string concatenation operators such as + or +=. Program performance can decrease if these methods are frequently called, such as when characters are added to a string in a tight loop.
 

docs/profiling/toc.yml

@@ -36,10 +36,10 @@
     items:
     - name: CPU usage
       href: cpu-usage.md
-    - name: Performance rules
+    - name: Performance insights
       items:
       - name: String concatenation
-        href: perf-rules-string-concatenation.md
+        href: perf-insights-string-concatenation.md
   - name: File IO
     href: use-file-io.md    
   - name: Memory usage