typo fix in core (#2987)

substrate/core/state-machine/src/changes_trie/build.rs

@@ -29,7 +29,7 @@ use crate::changes_trie::{AnchorBlockId, Configuration, Storage, BlockNumber};
 
 /// Prepare input pairs for building a changes trie of given block.
 ///
-/// Returns Err if storage error has occured OR if storage haven't returned
+/// Returns Err if storage error has occurred OR if storage haven't returned
 /// required data.
 /// Returns Ok(None) data required to prepare input pairs is not collected
 /// or storage is not provided.

substrate/core/state-machine/src/changes_trie/build_iterator.rs

@@ -15,7 +15,7 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Structures and functions to return blocks whose changes are to be included
-//! in given block' changes trie.
+//! in given block's changes trie.
 
 use crate::changes_trie::{Configuration, BlockNumber};
 

substrate/core/state-machine/src/changes_trie/changes_iterator.rs

@@ -98,7 +98,7 @@ pub fn key_changes_proof<S: Storage<H, Number>, H: Hasher, Number: BlockNumber>(
 	Ok(iter.extract_proof())
 }
 
-/// Check key changes proog and return changes of the key at given blocks range.
+/// Check key changes proof and return changes of the key at given blocks range.
 /// `max` is the number of best known block.
 /// Changes are returned in descending order (i.e. last block comes first).
 pub fn key_changes_proof_check<S: RootsStorage<H, Number>, H: Hasher, Number: BlockNumber>(

substrate/core/state-machine/src/changes_trie/prune.rs

@@ -145,7 +145,7 @@ fn pruning_range<Number: BlockNumber>(
 /// blocks. So we can only prune blocks that are earlier than B - max_digest_interval.
 /// The pruning_delay stands for number of max_digest_interval-s that we want to keep:
 /// 0 or 1: means that only last changes trie is guaranteed to exists;
-/// 2: the last chnages trie + previous changes trie
+/// 2: the last changes trie + previous changes trie
 /// ...
 fn max_digest_intervals_to_keep<Number: BlockNumber>(
 	min_blocks_to_keep: Number,