Fix broken path in Readme and fix graql syntax

[gowtham1997]

What is the goal of this PR?

Fix a broken link and the graql syntax of a simple query in the animaltrade KGCN example readme

What are the changes implemented in this PR?

Replaced the broken link.

The graql code match $t isa traded-item; limit 1; get; gives me a syntax error:

Error: syntax error at line 1: 
match $t isa traded-item; limit 1; get;
                          ^
no viable alternative at input 'match $t isa traded-item; limit'
syntax error at line 1: 
match $t isa traded-item; limit 1; get;
                          ^
no viable alternative at input 'match $t isa traded-item; limit'
All uncommitted data is cleared

so changing it to match $t isa traded-item; get; limit 1;

[jmsfltchr]

Thanks for the edit! This will be merged shortly