Fixes /swarm/join endpoint documentation
Fixes /swarm/join endpoint documentation

The JSON payload given in the API documentation is wrong, fixing it.

Signed-off-by: Vincent Demeester <87e1f221a672a14a323e57bb65eaea19d3ed3804@sbr.pm>
(cherry picked from commit 97c9491b0d395dc923e8b4e335839662c17aff46)

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