Fix broken links in README and main documentation page

[aoberoi]

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[aoberoi]

something about the CI tests is flaky, and should be investigated. we got one failure from NPM for an integrity check (SHA sums were not matching), and another as a timeout. unfortunately, i already restarted the builds so I don't have the logs available. if it happens again, i'll create a separate issue for them.

[codecov]

Codecov Report

Merging #763 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #763   +/-   ##
=======================================
  Coverage   97.85%   97.85%           
=======================================
  Files          15       15           
  Lines         652      652           
  Branches       26       26           
=======================================
  Hits          638      638           
  Misses         13       13           
  Partials        1        1

Flag	Coverage Δ
#eventsapi	95.62% <ø> (ø)	⬆️
#interactivemessages	99.18% <ø> (ø)	⬆️
#webapi	98.33% <ø> (ø)	⬆️
#webhook	90.69% <ø> (ø)	⬆️

---

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 7247d38...3a32c51. Read the comment docs.

[codecov]

Codecov Report

Merging #763 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #763   +/-   ##
=======================================
  Coverage   97.85%   97.85%           
=======================================
  Files          15       15           
  Lines         652      652           
  Branches       26       26           
=======================================
  Hits          638      638           
  Misses         13       13           
  Partials        1        1

Flag	Coverage Δ
#eventsapi	95.62% <ø> (ø)	⬆️
#interactivemessages	99.18% <ø> (ø)	⬆️
#webapi	98.33% <ø> (ø)	⬆️
#webhook	90.69% <ø> (ø)	⬆️

---

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 7247d38...3a32c51. Read the comment docs.