chore(cli): explain when --toolkit-stack-name applies (#18865)

Closes #18862.


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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: rix0rrr

packages/aws-cdk/bin/cdk.ts

@@ -70,7 +70,6 @@ async function parseCommandLineArguments() {
     .option('path-metadata', { type: 'boolean', desc: 'Include "aws:cdk:path" CloudFormation metadata for each resource (enabled by default)', default: true })
     .option('asset-metadata', { type: 'boolean', desc: 'Include "aws:asset:*" CloudFormation metadata for resources that uses assets (enabled by default)', default: true })
     .option('role-arn', { type: 'string', alias: 'r', desc: 'ARN of Role to use when invoking CloudFormation', default: undefined, requiresArg: true })
-    .option('toolkit-stack-name', { type: 'string', desc: 'The name of the CDK toolkit stack', requiresArg: true })
     .option('staging', { type: 'boolean', desc: 'Copy assets to the output directory (use --no-staging to disable, needed for local debugging the source files with SAM CLI)', default: true })
     .option('output', { type: 'string', alias: 'o', desc: 'Emits the synthesized cloud assembly into a directory (default: cdk.out)', requiresArg: true })
     .option('no-color', { type: 'boolean', desc: 'Removes colors and other style from console output', default: false })
@@ -95,6 +94,7 @@ async function parseCommandLineArguments() {
       .option('force', { alias: 'f', type: 'boolean', desc: 'Always bootstrap even if it would downgrade template version', default: false })
       .option('termination-protection', { type: 'boolean', default: undefined, desc: 'Toggle CloudFormation termination protection on the bootstrap stacks' })
       .option('show-template', { type: 'boolean', desc: 'Instead of actual bootstrapping, print the current CLI\'s bootstrapping template to stdout for customization', default: false })
+      .option('toolkit-stack-name', { type: 'string', desc: 'The name of the CDK toolkit stack to create', requiresArg: true })
       .option('template', { type: 'string', requiresArg: true, desc: 'Use the template from the given file instead of the built-in one (use --show-template to obtain an example)' }),
     )
     .command('deploy [STACKS..]', 'Deploys the stack(s) named STACKS into your AWS account', yargs => yargs
@@ -112,6 +112,7 @@ async function parseCommandLineArguments() {
       .option('parameters', { type: 'array', desc: 'Additional parameters passed to CloudFormation at deploy time (STACK:KEY=VALUE)', nargs: 1, requiresArg: true, default: {} })
       .option('outputs-file', { type: 'string', alias: 'O', desc: 'Path to file where stack outputs will be written as JSON', requiresArg: true })
       .option('previous-parameters', { type: 'boolean', default: true, desc: 'Use previous values for existing parameters (you must specify all parameters on every deployment if this is disabled)' })
+      .option('toolkit-stack-name', { type: 'string', desc: 'The name of the existing CDK toolkit stack (only used for app using legacy synthesis)', requiresArg: true })
       .option('progress', { type: 'string', choices: [StackActivityProgress.BAR, StackActivityProgress.EVENTS], desc: 'Display mode for stack activity events' })
       .option('rollback', {
         type: 'boolean',
@@ -158,6 +159,7 @@ async function parseCommandLineArguments() {
       .option('exclusively', { type: 'boolean', alias: 'e', desc: 'Only deploy requested stacks, don\'t include dependencies' })
       .option('change-set-name', { type: 'string', desc: 'Name of the CloudFormation change set to create' })
       .option('force', { alias: 'f', type: 'boolean', desc: 'Always deploy stack even if templates are identical', default: false })
+      .option('toolkit-stack-name', { type: 'string', desc: 'The name of the existing CDK toolkit stack (only used for app using legacy synthesis)', requiresArg: true })
       .option('progress', { type: 'string', choices: [StackActivityProgress.BAR, StackActivityProgress.EVENTS], desc: 'Display mode for stack activity events' })
       .option('rollback', {
         type: 'boolean',