Missing cli watch option described in documentation

[Daniel Emery]

Describe the bug
The documentation describes a watch option when using the cli but it doesn't exist.

To Reproduce
Steps to reproduce the behavior:

1. Read the documentatiion at https://www.npmjs.com/package/swagger-jsdoc/v/1.9.1 (see the last point of Using a CLI)
2. Attempt to run the command as described, see an example from my project:

   swagger-jsdoc -d ./src/rest/internal/swagger-definition.js './src/rest/internal/**/*.ts' -o ./src/rest/internal/swagger.json -w

3. See error

   error: unknown option '-w'
   

4. Run help and note option is not described

   user@shell: npx swagger-jsdoc --help
   
   Usage: swagger-jsdoc [options] <path ...>
   
   Options:
     -V, --version                            output the version number
     -d, --definition <swaggerDefinition.js>  Input swagger definition.
     -o, --output [swaggerSpec.json]          Output swagger specification.
     -h, --help                               display help for command
   

Expected behavior
A watch process starts and monitors files specified in glob for changes, regenerating the swagger specification as required.

Screenshots
N/A

Desktop (please complete the following information):
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Smartphone (please complete the following information):
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Additional context
I had a look through the history and found that it used to exist but was removed in #121 without comment.

[Daniel Emery]

Suggestions

1. Simply remove documentation to not confuse the next person looking for a watch option
2. Replace the watch details with a simple explanation of how to use nodemon or bash etc to achieve the same result
3. Re-implement the watch flag and functionality

If the answer is (1) or (2) I am happy to raise a PR, we will probably end up implementing a watch outside of the cli for our use in the short term anyway.

If the answer is (3) I probably don't have the time or the context to help out (I would suggest if it can be achieved with (2) it might be the easier to maintain solution anyway)