[doc] Add docs of options of piped&launcher

[Tetsuya Kikuchi]

What would you like to be added:

Add docs of what launch options piped&launcher have like the Configuration Reference.

We need to explain options defined in:

• launcher:
  https://github.com/pipe-cd/pipecd/blob/master/pkg/app/launcher/cmd/launcher/launcher.go#L60-L87
• piped:
  

  pipecd/pkg/app/piped/cmd/piped/piped.go

  Lines 87 to 102 in 9e5ad3d

   type piped struct { 
   	configFile      string 
   	configData      string 
   	configGCPSecret string 
   	configAWSSecret string 
    
   	insecure                             bool 
   	certFile                             string 
   	adminPort                            int 
   	toolsDir                             string 
   	enableDefaultKubernetesCloudProvider bool 
   	gracePeriod                          time.Duration 
   	addLoginUserToPasswd                 bool 
   	launcherVersion                      string 
   	maxRecvMsgSize                       int 
   } 

Why is this needed:

When users setup piped/launcher, they need to understand "How to pass piped-config?" and so on,
although there are guides of install-piped showing concrete usage (e.g. https://github.com/pipe-cd/pipecd/blob/master/docs/content/en/docs-v0.46.x/installation/install-piped/installing-on-kubernetes.md)