fix: add helplink for devchannel actions

[nliu-ms]

https://msazure.visualstudio.com/Microsoft%20Teams%20Extensibility/_workitems/edit/32019035

1. Add helplink
2. Update strings

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.02%. Comparing base (8ee93cf) to head (76e77cb).

Additional details and impacted files

@@           Coverage Diff           @@
##              dev   #13822   +/-   ##
=======================================
  Coverage   90.02%   90.02%           
=======================================
  Files         648      648           
  Lines       38754    38756    +2     
  Branches     7573     7576    +3     
=======================================
+ Hits        34887    34889    +2     
  Misses       1755     1755           
  Partials     2112     2112           

Files with missing lines	Coverage Δ
.../fx-core/src/component/driver/devChannel/create.ts	95.55% <100.00%> (+0.10%)	⬆️
.../fx-core/src/component/driver/devChannel/errors.ts	100.00% <100.00%> (ø)
...core/src/component/driver/devChannel/installApp.ts	97.40% <100.00%> (+0.03%)	⬆️

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