Clarify mesh configuration values.

[SeppoTakalo]

Description

A number of the configuration values in the mbed_lib.json files for Mesh contain 'help' fields which were missing acceptable ranges for their associated values.
This PR adds the missing ranges.

Pull request type

[X] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 1854
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6745/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1498
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6745/

[mbed-ci]

Test : SUCCESS

Build number : 1662
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6745/1662

[cmonr]

@SeppoTakalo With future PRs, please be sure to indicate the type of PR is being submitted. This PR has been modified as an example.

[SeppoTakalo]

@cmonr Thanks for notifying. I removed the template completely because there were nothing related to documentation. But as this is correction of the documentation the [ x ] Fix is the correct category.

[adbridge]

@SeppoTakalo The template should be left as is and a Description added where stated along with the PR type, otherwise the automated scripts that will soon run against all PRs will fail...In fact it explicitly gives this advice in the PR template itself.....
I've also updated the description itself to make it clear the level of detail we will be expecting here going forward.

[mbed-ci]

Exporter Build : FAILURE

Build number : 1523
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6745/