Few {@inheritdoc} formatting fixes

Appears these type of documentation fixes should be classified as bug fixes.

Thanks @malavya for rolling a patch with additional {@inheritdoc} changes. Unfortunately the three changes you added are subtly wrong. Your additions caught the @inheritDoc errors (with a capital 'D'). The proper string is '{@inheritdoc}' (with a lower case 'd'). Hence I am setting back to 'Needs work.'

Checking the core code base, I see that there are approximately ten additional files that need to be changed from '{@inheritDoc}' to the documentation standard of '{@inheritdoc}'. I am unsure of how many files we should include in a simple documentation patch like this before it becomes too big or disruptive. That is why I was targeting about ten files in the initial patch. Perhaps one of the core committers can give some feedback?

@jodgdon: If you see this comment, perhaps you can also advise if '@inheritdoc' is permissible in our javascript documentation standards. Both of the patches in this issue only address *.php files. There are approximately a dozen *.js files that might need to be addressed as well.

Here is an updated patch taking into account both comments #6 and #7. The attached interdiff is against the original patch since the changes in #3 were slightly wrong (capital 'D' vis-a-vis lower case 'd'). Thanks for your help with this issue @malavya.