undefined symbol TINYCBOR during doc build

[dbkinder]

Describe the bug
Getting an unexpected warning when generating documentation with "make htmldocs"

To Reproduce

~/zephyr$ make htmldocs-fast
mkdir -p doc/_build && cmake -GNinja -DKCONFIG_TURBO_MODE=1 -DDOC_TAG=development -DSPHINXOPTS=-q -Bdoc/_build -Hdoc/ && ninja -C doc/_build htmldocs
-- Zephyr base: /home/dbkinder/zephyr
Zephyr version: 1.14.0
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.6.7", minimum required is "3.4") 
-- Found Doxygen: /usr/bin/doxygen (found version "1.8.13") found components:  doxygen 
-- Found LATEX: /usr/bin/latex   
-- Configuring done
-- Generating done
-- Build files have been written to: /home/dbkinder/zephyr/doc/_build
ninja: Entering directory `doc/_build'
[2/5] Running genrest.py Kconfig /home/dbkinder/zephyr/doc/_build/rst/doc/reference/kconfig/
warning: undefined symbol TINYCBOR:

- Referenced at ext/lib/mgmt/mcumgr/Kconfig:18:

config MCUMGR
	bool
	prompt "mcumgr Support"
	select TINYCBOR
	help
	  This option enables the mcumgr management library.

No new errors reported after that.

[carlescufi]

Please run west update and this will fix it, assuming you have west set up correctly.