[docs] Fix prefer-while docs (#3888)

- Updated docs to make sense semantically (use vars that should exist in the scope of each for-loop)
- Updated tests with same issue

src/rules/code-examples/preferWhile.examples.ts

@@ -25,12 +25,12 @@ export const codeExamples = [
             "rules": { "prefer-while": true }
         `,
         pass: Lint.Utils.dedent`
-            for(let x = 1; x < 10; x++) {
-                console.log(x);
+            for(let i = 1; i < 10; i++) {
+                console.log(i);
             }
 
-            for (let i = 0; i < 10; x+=1) {
-                console.log(x);
+            for (let i = 0; i < 10; i+=1) {
+                console.log(i);
             }
 
             for (let i = 0; i < 10;) {
@@ -39,11 +39,11 @@ export const codeExamples = [
         `,
         fail: Lint.Utils.dedent`
             for(;;) {
-                console.log(x);
+                console.log('Hello World');
             }
 
             for(;true===true;) {
-                console.log(x);
+                console.log('Hello World');
             }
         `,
     },

test/rules/prefer-while/test.ts.fix

@@ -1,21 +1,21 @@
 // for loops without an initializer, termination condition, and incrementor should be updated
 while (true) {
-    console.log(x);
+    console.log('Hello World');
 }
 
 // for loops without an initializer and incrementor should be updated
 while (true===true) {
-    console.log(x);
+    console.log('Hello World');
 }
 
 // for loops with an initializer, termination condition, and incrementor using '++' should remain untouched
-for(let x = 1; x < 10; x++) {
-    console.log(x);
+for (let i = 1; i < 10; i++) {
+    console.log(i);
 }
 
 // for loops with an initializer, termination condition, and incrementor using '+=' should remain untouched
-for (let i = 0; i < 10; x+=1) {
-    console.log(x);
+for (let i = 0; i < 10; i+=1) {
+    console.log(i);
 }
 
 // for loops with an initializer and termination condition should remain untouched

test/rules/prefer-while/test.ts.lint

@@ -1,23 +1,23 @@
 // for loops without an initializer, termination condition, and incrementor should be updated
 for(;;) {
 ~~~~~~~   [Prefer `while` loops instead of `for` loops without an initializer and incrementor.]
-    console.log(x);
+    console.log('Hello World');
 }
 
 // for loops without an initializer and incrementor should be updated
 for(;true===true;) {
 ~~~~~~~~~~~~~~~~~~   [Prefer `while` loops instead of `for` loops without an initializer and incrementor.]
-    console.log(x);
+    console.log('Hello World');
 }
 
 // for loops with an initializer, termination condition, and incrementor using '++' should remain untouched
-for(let x = 1; x < 10; x++) {
-    console.log(x);
+for (let i = 1; i < 10; i++) {
+    console.log(i);
 }
 
 // for loops with an initializer, termination condition, and incrementor using '+=' should remain untouched
-for (let i = 0; i < 10; x+=1) {
-    console.log(x);
+for (let i = 0; i < 10; i+=1) {
+    console.log(i);
 }
 
 // for loops with an initializer and termination condition should remain untouched