updates to oauth docs

for token sending and manual generation

refs CNVS-13008

test plan: n/a

Change-Id: I74ad75f6fad0033b7407bcc9555ffe71451470ef
Reviewed-on: https://gerrit.instructure.com/36412
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Reviewed-by: Nick Cloward <ncloward@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>
update oauth docs for state param

refs CNVS-13008

test plan: n/a

Change-Id: Ia37c9500a47bde2ee758da331e03d3a8bdbaf7d7
Reviewed-on: https://gerrit.instructure.com/36413
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Nick Cloward <ncloward@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>