[SPARK-19639][SPARKR][Example]:Add spark.svmLinear example and update vignettes

[wangmiao1981]

What changes were proposed in this pull request?

We recently add the spark.svmLinear API for SparkR. We need to add an example and update the vignettes.

How was this patch tested?

Manually run example.

[SparkQA]

Test build #73025 has finished for PR 16969 at commit 6e54a4d.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[felixcheung]

are we merging this after #16968?

[felixcheung]

shouldn't Linear go before Logistic?

[felixcheung]

linear kernels?

[felixcheung]

we actually don't have support for one-vs-the-rest strategy in R at the moment (existing JIRA or design still open), so perhaps it's best we don't reference that here

[felixcheung]

should it go with maxIter = 10 here too?

[felixcheung]

linearSvc -> svmLinear? or Linear SVM?

[SparkQA]

Test build #73040 has finished for PR 16969 at commit 959b0a1.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[felixcheung]

LGTM, with a few comments, and need to add back R section in ml programming guide and wait till the other PR is merged first

[felixcheung]

this feels minor to me, but there was feedback that these section should be in the same order they are listed (ie sorted alphabetically)

[felixcheung]

add sparkR.session.stop() at the end

[SparkQA]

Test build #73077 has finished for PR 16969 at commit ab252ee.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #73072 has finished for PR 16969 at commit 864f2c3.

• This patch passes all tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[felixcheung]

I assume 2c3 is before you rebase.

[felixcheung]

merged to master. I figure you could update the programming guide after the other PR is merged