Feature request: show doc summary under each symbol

[alecthomas]

Having a one-line summary for each symbol displayed under the symbol would be very useful, as when browsing API's it's often difficult to tell what a type/function will do without reading the doc. eg. Instead of

func MyFunc()

It would display:

func MyFunc()
  This function does something really awesome.

[zigo101]

I couldn't make a decision whether this is good or not now.
I will add a hidden option to control this behavior so that we can evaluate which default is better.

Please note in Golds generated docs, there is no the index section. Each symbol acts as the index of itself.

[zigo101]

@alecthomas
I found there is a difficulty to implement this: how the one line text should be extracted from the symbol docs?
A simple answer might be to use the text before the first .. However, this is not true for non-English docs.

And this proposal makes there are 3 showing status of symbol docs: collapse all / show one line / expand all.
This increases the difficulty of UE design much.

Now, symbol docs showing statuses could be toggled by pressing the t key.
Do you think it is acceptable?