Update index-creation.txt

fix typos

Author: RafaelGreen1

source/core/index-creation.txt

@@ -168,7 +168,7 @@ The build process is summarized as follows:
    the index build.
 
 #. The secondaries start the index build after they replicate the 
-   "startIndexBuild oplog entry.
+   "startIndexBuild" oplog entry.
 
 #. Each member "votes" to commit the build once it finishes indexing 
    data in the collection. 
@@ -239,7 +239,7 @@ down cleanly during the index build and the
 :ref:`commitQuorum <createIndexes-cmd-commitQuorum>` is set to the
 default ``votingMembers``, then the index build progress is saved to
 disk. The :binary:`~bin.mongod` automatically recovers the index build
-when it is restarted and continues from the saved checkpoint. In earler
+when it is restarted and continues from the saved checkpoint. In earlier
 versions, if the index build was interrupted it had to be restarted
 from the beginning.
 
@@ -251,7 +251,7 @@ down cleanly during the index build and the
 :ref:`commitQuorum <createIndexes-cmd-commitQuorum>` is set to the
 default ``votingMembers``, then the index build progress is saved to
 disk. The :binary:`~bin.mongod` automatically recovers the index build
-when it is restarted and continues from the saved checkpoint. In earler
+when it is restarted and continues from the saved checkpoint. In earlier
 versions, if the index build was interrupted it had to be restarted
 from the beginning.