feat(docs): add right nav

[liushuiyuan001]

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[liushuiyuan001]

@JeremyWuuuuu

Can I copy your code and change it a bit? If not, I will cancel. I hope to have this feature in version 2x
Below is your pr
element-plus/element-plus#1341

[liushuiyuan001]

@cs1707 Can the pr be merged?

[jw-foss]

@JeremyWuuuuu

Can I copy your code and change it a bit? If not, I will cancel. I hope to have this feature in version 2x
Below is your pr
element-plus/element-plus#1341

This work is done by @Ryan2128, you might mention the reference in the code. That'd be ok to us.

[liushuiyuan001]

@JeremyWuuuuu
Can I copy your code and change it a bit? If not, I will cancel. I hope to have this feature in version 2x
Below is your pr
element-plus/element-plus#1341

This work is done by @Ryan2128, you might mention the reference in the code. That'd be ok to us.

OK,Thx.
@Ryan2128. Can I copy your code ?

[cs1707]

@cs1707 Can the pr be merged?

Dear @liushuiyuan001 . Thanks for your contribution.
Some styles need to be modified.

[liushuiyuan001]

@cs1707 Can the pr be merged?

Dear @liushuiyuan001 . Thanks for your contribution.
Some styles need to be modified.

OK.I will fix

[liushuiyuan001]

@media (max-width: 1490px) {  
 .right-nav {    
   display: none; 
 }
}

@cs1707 The whole style seems to have some problems. I can only fit the big screen.It's OK? Otherwise the content will be covered.

[cs1707]

@media (max-width: 1490px) {  
 .right-nav {    
   display: none; 
 }
}

@cs1707 The whole style seems to have some problems. I can only fit the big screen.It's OK? Otherwise the content will be covered.

@media (max-width: 1490px) {  
 .right-nav {    
   display: none; 
 }
}

@cs1707 The whole style seems to have some problems. I can only fit the big screen.It's OK? Otherwise the content will be covered.

I think the style still needs to be optimized. eg: position, scrollbar. And the error reporting in the console needs to be fixed.

[liushuiyuan001]

@cs1707
I just fix error reporting and fix style.It' OK ? What should I do ?