fix typo in "readonly" flag in documentation
fix typo in "readonly" flag in documentation

the flag is named '--read-only', not '--readonly'

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>
(cherry picked from commit ac12696ff48aeb115e3d9ce3b13cfa54342b5aee)
Signed-off-by: Tibor Vass <3f1326dff4d85ad4ec938fb33f64575ace96db26@docker.com>

BSWANG/denverdino.github.io,londoncalling/docker.github.io,rillig/docker.github.io,phiroict/docker,londoncalling/docker.github.io,docker-zh/docker.github.io,bdwill/docker.github.io,LuisBosquez/docker.github.io,denverdino/denverdino.github.io,phiroict/docker,denverdino/denverdino.github.io,Shopify/docker,medallia/docker,shin-/docker.github.io,aduermael/docker.github.io,docker/docker.github.io,danix800/docker.github.io,JimGalasyn/docker.github.io,medallia/docker,menglingwei/denverdino.github.io,thaJeztah/docker.github.io,jzwlqx/denverdino.github.io,alexisbellido/docker.github.io,alexisbellido/docker.github.io,LuisBosquez/docker.github.io,johnstep/docker.github.io,johnstep/docker.github.io,Shopify/docker,shubheksha/docker.github.io,joaofnfernandes/docker.github.io,joaofnfernandes/docker.github.io,LuisBosquez/docker.github.io,anweiss/docker.github.io,JimGalasyn/docker.github.io,bdwill/docker.github.io,denverdino/denverdino.github.io,joeuo/docker.github.io,gdevillele/docker.github.io,troy0820/docker.github.io,gdevillele/docker.github.io,docker/docker.github.io,LuisBosquez/docker.github.io,bdwill/docker.github.io,docker/docker.github.io,phiroict/docker,anweiss/docker.github.io,docker/docker.github.io,troy0820/docker.github.io,alexisbellido/docker.github.io,sanscontext/docker.github.io,menglingwei/denverdino.github.io,BSWANG/denverdino.github.io,docker-zh/docker.github.io,thaJeztah/docker.github.io,johnstep/docker.github.io,docker-zh/docker.github.io,docker-zh/docker.github.io,sanscontext/docker.github.io,gdevillele/docker.github.io,denverdino/docker.github.io,shin-/docker.github.io,londoncalling/docker.github.io,denverdino/denverdino.github.io,londoncalling/docker.github.io,jzwlqx/denverdino.github.io,troy0820/docker.github.io,jzwlqx/denverdino.github.io,phiroict/docker,docker/docker.github.io,jzwlqx/denverdino.github.io,danix800/docker.github.io,shubheksha/docker.github.io,danix800/docker.github.io,johnstep/docker.github.io,aduermael/docker.github.io,rillig/docker.github.io,denverdino/docker.github.io,anweiss/docker.github.io,joaofnfernandes/docker.github.io,shubheksha/docker.github.io,gdevillele/docker.github.io,rillig/docker.github.io,stainboy/docker,alexisbellido/docker.github.io,shin-/docker.github.io,joaofnfernandes/docker.github.io,joaofnfernandes/docker.github.io,menglingwei/denverdino.github.io,shubheksha/docker.github.io,shin-/docker.github.io,troy0820/docker.github.io,bdwill/docker.github.io,BSWANG/denverdino.github.io,shin-/docker.github.io,jzwlqx/denverdino.github.io,sanscontext/docker.github.io,Shopify/docker,stainboy/docker,joeuo/docker.github.io,medallia/docker,johnstep/docker.github.io,BSWANG/denverdino.github.io,denverdino/docker.github.io,shubheksha/docker.github.io,JimGalasyn/docker.github.io,thaJeztah/docker.github.io,denverdino/docker.github.io,JimGalasyn/docker.github.io,alexisbellido/docker.github.io,menglingwei/denverdino.github.io,JimGalasyn/docker.github.io,danix800/docker.github.io,aduermael/docker.github.io,stainboy/docker,anweiss/docker.github.io,BSWANG/denverdino.github.io,bdwill/docker.github.io,docker-zh/docker.github.io,gdevillele/docker.github.io,menglingwei/denverdino.github.io,sanscontext/docker.github.io,londoncalling/docker.github.io,sanscontext/docker.github.io,rillig/docker.github.io,thaJeztah/docker.github.io,denverdino/docker.github.io,joeuo/docker.github.io,denverdino/denverdino.github.io,joeuo/docker.github.io,joeuo/docker.github.io,anweiss/docker.github.io,phiroict/docker,LuisBosquez/docker.github.io,thaJeztah/docker.github.io,medallia/docker,aduermael/docker.github.io