remove double spaces where it wasn't necessary

vignettes/datatable-importing.Rmd

@@ -21,11 +21,11 @@ Importing `data.table` is no different from importing other R packages. This vig
 
 ## Why to import `data.table`
 
-One of the biggest features of `data.table` is its concise syntax which makes exploratory analysis faster and easier to write and perceive; this convenience  can drive packages authors to use `data.table` in their own packages. Another maybe even more important reason is high performance. When outsourcing heavy computing tasks from your package to `data.table`, you usually get top performance without needing to re-invent any high of these numerical optimization tricks on your own.
+One of the biggest features of `data.table` is its concise syntax which makes exploratory analysis faster and easier to write and perceive; this convenience can drive packages authors to use `data.table` in their own packages. Another maybe even more important reason is high performance. When outsourcing heavy computing tasks from your package to `data.table`, you usually get top performance without needing to re-invent any high of these numerical optimization tricks on your own.
 
 ## Importing `data.table` is easy
 
-It is very easy to use `data.table` as a dependency due to the fact that `data.table` does not have any of its own dependencies. This statement is valid for both operating system dependencies and R dependencies. It means that if you have R installed on your machine, it already has everything  needed to install `data.table`. This also means that adding `data.table` as a dependency of your package will not result in a chain of other recursive dependencies to install, making it very convenient for offline installation.
+It is very easy to use `data.table` as a dependency due to the fact that `data.table` does not have any of its own dependencies. This statement is valid for both operating system dependencies and R dependencies. It means that if you have R installed on your machine, it already has everything needed to install `data.table`. This also means that adding `data.table` as a dependency of your package will not result in a chain of other recursive dependencies to install, making it very convenient for offline installation.
 
 ## `DESCRIPTION` file {DESCRIPTION}