Some tweaks to the docs

[wmvanvliet]

• Fix some typos and update link to EEG data (physionet has a new URL)
• Add bctpy to the dependency list in INSTALL.md

[codecov]

Codecov Report

Merging #80 (15a830a) into master (8a2b0e4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   93.23%   93.23%           
=======================================
  Files          73       73           
  Lines        2334     2334           
=======================================
  Hits         2176     2176           
  Misses        158      158           

---

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 8a2b0e4...15a830a. Read the comment docs.

[coveralls]

Pull Request Test Coverage Report for Build 769

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.225%

---

Totals
Change from base Build 758:	0.0%
Covered Lines:	2174
Relevant Lines:	2332

---

💛 - Coveralls