Remove a dead link from docs (#1563)

* Update intro.zh-cn.md

remove link

* Update intro.md

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* Change link to point to original paper

doc/intro.md

@@ -249,7 +249,7 @@ the number. We won't elaborate on the range proof, but you just need to know
 that for any `r.G + v.H` we can build a proof that will show that _v_ is greater than
 zero and does not overflow.
 
-It's also important to note that in order to create a valid range proof from the example above, both of the values 113 and 28 used in creating and signing for the excess value must be known. The reason for this, as well as a more detailed description of range proofs are further detailed in the [range proof primer](rangeproofs.md).
+It's also important to note that in order to create a valid range proof from the example above, both of the values 113 and 28 used in creating and signing for the excess value must be known. The reason for this, as well as a more detailed description of range proofs are further detailed in the [range proof paper](https://eprint.iacr.org/2017/1066.pdf).
 
 <a name="transaction-conclusion"></a>
 ### Putting It All Together

doc/intro.zh-cn.md

@@ -158,7 +158,7 @@ _X_, 上述加法的输出值，是对所有人可见的。 但是值3只有你
 为了解决这个问题，MimbleWimble利用了另一个加密概念（也来自机密交易），称为范围证明：一个数字落在给定范围内的证明，而不会泄露数字。 
 我们不会详细说明范围证明，您只需要知道，对于任何`r.G + v.H`，我们都可以创建一个证明，证明 _v_ 大于零且不会溢出。
 
-同样重要的是要注意，为了从上面的示例中创建有效的范围证明，必须知道在创建和签署excess value时使用的值113和28。 其原因以及范围证明的更详细描述在[range proof primer](rangeproofs.md)中进一步详述。
+同样重要的是要注意，为了从上面的示例中创建有效的范围证明，必须知道在创建和签署excess value时使用的值113和28。 其原因以及范围证明的更详细描述在[range proof paper](https://eprint.iacr.org/2017/1066.pdf)中进一步详述。
 
 <a name="transaction-conclusion"></a>
 ### 小结