Apply suggestions from code review by @einverne

Co-authored-by: Ein Verne <git@einverne.info>

pages/common/dvc-add.md

@@ -1,6 +1,6 @@
 # dvc add
 
-> Adds changed files to the index.
+> Add changed files to the index.
 > More information: <https://dvc.org/doc/command-reference/add>.
 
 - Add a single target file to the index:

pages/common/dvc-init.md

@@ -1,6 +1,6 @@
 # dvc init
 
-> Initializes a new local DVC repository.
+> Initialize a new local DVC repository.
 > More information: <https://dvc.org/doc/command-reference/init>.
 
 - Initialize a new local repository: