Merge rust-bitcoin#4418: docs: correction comments in check-semver-feature.sh

a91e4de correction comments check-semver-feature.sh (Alex Pikme)

Pull request description:

  `presence non-additive` -` presence of non-additive `-- **add of**
  `non-addivite` - `non-additive` -- **fix error**

ACKs for top commit:
  apoelstra:
    ACK a91e4de; successfully ran local tests
  tcharding:
    ACK a91e4de

Tree-SHA512: d179d2cf8e076d0b2143145d86135a992e66f62d30b777fd50d2d3bb2026e738f6e0d61423ba84d4c7b7dc62f881ec6f8dad2d9bcc5ea7e1289e47e962ad3c40

Author: apoelstra

contrib/check-semver-feature.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 #
 # Checks semver compatibility between the `--no-features` and `all-features`.
-# This is important since it tests for the presence non-additive cargo features.
+# This is important since it tests for the presence of non-additive cargo features.
 #
 # Under the hood uses cargo semver-checks to check for breaking changes.
 # We cannot use it directly since it only supports checking against published
@@ -40,7 +40,7 @@ main() {
     generate_json_files_all_features "bitcoin-io"
     generate_json_files_no_default_features "bitcoin-io"
 
-    # Check for API semver non-addivite cargo features on all the generated JSON files above.
+    # Check for API semver non-additive cargo features on all the generated JSON files above.
     run_cargo_semver_check "bitcoin"
     run_cargo_semver_check "base58ck"
     run_cargo_semver_check "bitcoin_hashes"