[clang-tidy][NFC] Update identifier-length.rst (#93467)

Swapped code blocks of parameter and variable, which have been confused
(in a clang-tidy doc file)

Author: mattanelkaim

clang-tools-extra/docs/clang-tidy/checks/readability/identifier-length.rst

@@ -28,10 +28,7 @@ The following options are described below:
 
     .. code-block:: c++
 
-         int doubler(int x)   // warns that x is too short
-         {
-            return 2 * x;
-         }
+      int i = 42;    // warns that 'i' is too short
 
     This check does not have any fix suggestions in the general case since
     variable names have semantic value.
@@ -50,7 +47,10 @@ The following options are described below:
 
     .. code-block:: c++
 
-      int i = 42;    // warns that 'i' is too short
+         int doubler(int x)   // warns that x is too short
+         {
+            return 2 * x;
+         }
 
     This check does not have any fix suggestions in the general case since
     variable names have semantic value.