docs: Adding documentation for concatAll operator.

[sumitarora]

Fixes: #64

[sumitarora]

@ashwin-sureshkumar @ladyleet If this is what's needed for docs for operator's I will start doing PR's for others too 😄

[codecov-io]

Codecov Report

Merging #134 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #134   +/-   ##
=======================================
  Coverage   86.88%   86.88%           
=======================================
  Files           4        4           
  Lines          61       61           
  Branches        7        7           
=======================================
  Hits           53       53           
  Misses          5        5           
  Partials        3        3

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 86bdde6...3a77c2d. Read the comment docs.

[btroncone]

lgtm 👍

[btroncone]

@ladyleet Any objections?

[ashwin-sureshkumar]

@btroncone - In the existing docs there is a return type specified for operator which is missing in the OperatorDoc, is that by design or we need to add that section ?

[btroncone]

I don't think it's necessary, to me it's covered by the operator signature. eg public combineAll(project: function): Observable.

[sumitarora]

@btroncone @ashwin-sureshkumar One thing I noticed is the walkthrough.extras section is not getting rendered. Is someone working on that?

[btroncone]

@sumitarora Creating a PR for this right now.

[ladyleet]

LGTM! Thx @sumitarora and thx @ashwin-sureshkumar for getting Sumit involved! :) Thx @btroncone for reviewing the PR.