Merge #624: doc/compiler.md:fix taproot_compiler.pdf link

eb10eb2 doc/compiler.md:fix taproot_compiler.pdf link (@RandyMcMillan)

Pull request description:

ACKs for top commit:
  tcharding:
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  apoelstra:
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Tree-SHA512: 3065221517c56dd65c5b6e378e4023487af9ca532fc36844394bc393c6cda76cc543da09454a03a33b587913349c0a476fcf7d2f062e3554ac032c13a25416e8

Author: apoelstra

doc/compiler.md

@@ -32,9 +32,9 @@ to re-arrange the policy tree to produce a even more efficient Miniscript. When
 It is possible that higher weight, but lower opcode exists sub-compilation might be best compilation, because the smaller weight sub-policy compilation that we chose exceeds the op-code count. There is also a similar issue with initial stack element count. The compiler does not try to optimize for these cases. If the final compiler output is not a valid Miniscript, it will simply fail and not try sub-optimal compilation that could fit inside these resource limits.
 
 These problems are addressed to a large extent with taproot descriptors as the resource limitations are either really large or completely removed.
-This library also supports a taproot descriptor compiler. The details of taproot compiler are can be found in the [taproot compiler document](doc/taproot_compiler.md).
+This library also supports a taproot descriptor compiler. The details of taproot compiler are can be found in the [taproot compiler document](./taproot_compiler.pdf).
 
 ### Non-determinism and stability guarantees of compiler
 
 The compiler outputs are not stable. They can change from version to version, machine to machine or even execution to execution on the same machine. The rust and C++ versions can produce different outputs even if the policy is the same. There could also be other implementations of compiler optimizing for different resource limits.
-However, the compiler will **always** output a valid Miniscript which might not be the same as some previous execution. As a simple example, `and_b(A,B)` could become `and_b(B,A)`. Therefore, it is **not recommended** to use policy as a stable identifier for a Miniscript. You should use the policy compiler once, and then use the Miniscript output as a stable identifier.
+However, the compiler will **always** output a valid Miniscript which might not be the same as some previous execution. As a simple example, `and_b(A,B)` could become `and_b(B,A)`. Therefore, it is **not recommended** to use policy as a stable identifier for a Miniscript. You should use the policy compiler once, and then use the Miniscript output as a stable identifier.