docs: Documentation only changes

PERFORMANCE.md

@@ -23,7 +23,7 @@ The rest of this document is the planned or completed actions for the above-list
 ## Cleanup
 
 Done in branch `cleanup_deps`:
-  * Fixed up dependeny management (tmlibs/db etc in glide/vendor)
+  * Fixed up dependency management (tmlibs/db etc in glide/vendor)
   * Updated Makefile (test, bench, get_deps)
   * Fixed broken code - `looper.go` and one benchmark didn't run
 

cmd/iaviewer/README.md

@@ -6,7 +6,7 @@ Below is a brief introduction to the tool.
 
 ## Installation
 
-Once this is merged into the offical repo, master, you should be able to do:
+Once this is merged into the official repo, master, you should be able to do:
 
 ```shell
 go get github.com/cosmos/iavl

immutable_tree.go

@@ -208,7 +208,7 @@ func (t *ImmutableTree) Get(key []byte) ([]byte, error) {
 
 	// otherwise skipFastStorageUpgrade is true or
 	// the cached node was updated later than the current tree. In this case,
-	// we need to use the regular stategy for reading from the current tree to avoid staleness.
+	// we need to use the regular strategy for reading from the current tree to avoid staleness.
 	_, result, err := t.root.get(t, key)
 	return result, err
 }