Developer instructions on building `azureml` package

Make sure below packages are installed.
```
install.packages('devtools')
```
Run the following to build the code. The R package file will be created at package_location. We can now either upload it to a blob store, publish it to CRAN or install directly from the file.
```
setwd('<repo_root>')

# Generate .Rd files in man/ and NAMESPACE
roxygen2::roxygenise()

# Build the R package
package_location <- devtools::build()
```
To install the package from the .tar.gz file in the filesystem, do:
```
install.packages(package_location, repos = NULL)
```
To install from a url:
```
install.packages(package_url, repos = NULL)
```
If you already have the package loaded in your R session, you may want to remove it from the session to use the new one. This can be done by the following:
```
detach("package:azuremlsdk", unload = TRUE)
```