Pre-0.3.0 changes

[str4d]

• Fix an intra-doc link.
• Add feature flags to docs.rs documentation.

[str4d]

You can test this PR locally with:

RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features

[codecov]

Codecov Report

Merging #281 into master will increase coverage by 0.00%.
The diff coverage is 84.91%.

@@           Coverage Diff           @@
##           master     #281   +/-   ##
=======================================
  Coverage   66.02%   66.03%           
=======================================
  Files         101      101           
  Lines       13214    13215    +1     
=======================================
+ Hits         8725     8726    +1     
  Misses       4489     4489           

Impacted Files	Coverage Δ
bls12_381/src/g1.rs	71.52% <ø> (ø)
bls12_381/src/g2.rs	69.04% <ø> (ø)
bls12_381/src/pairings.rs	58.67% <ø> (ø)
jubjub/src/lib.rs	56.62% <ø> (ø)
zcash_primitives/src/note_encryption.rs	77.29% <ø> (+0.06%)	⬆️
zcash_primitives/src/prover.rs	30.76% <ø> (ø)
...imitives/src/test_vectors/pedersen_hash_vectors.rs	100.00% <ø> (ø)
zcash_primitives/src/transaction/components.rs	35.21% <ø> (ø)
zcash_proofs/src/lib.rs	69.69% <ø> (ø)
zcash_proofs/src/prover.rs	65.85% <ø> (ø)
... and 10 more

---

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[daira]

utACK

[daira]

Tested ACK.