DOC: Side bar and main page fixes

[rmukh]

Summary

Fixes # .

List of changes proposed in this PR (pull-request)

• Fixes the problem that sidebar blocks are not available and links are not clickable.
• Remove unsupported property from a.navbar. Currently, color: on the main page is empty.

Moved sidebar elements on top of the layout file according to https://github.com/sphinx-doc/sphinx/blob/master/doc/_themes/sphinx13/layout.html

Acknowledgment

• (Mandatory) I acknowledge that this contribution will be available under the Apache 2 license.

[codecov]

Codecov Report

Merging #3397 (5587242) into master (eab4b2a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3397   +/-   ##
=======================================
  Coverage   65.20%   65.20%           
=======================================
  Files         307      307           
  Lines       40457    40457           
  Branches     5350     5350           
=======================================
  Hits        26379    26379           
- Misses      13003    13007    +4     
+ Partials     1075     1071    -4     

Flag	Coverage Δ
unittests	64.93% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
nipype/algorithms/icc.py	57.53% <0.00%> (ø)
nipype/interfaces/fsl/utils.py	63.76% <0.00%> (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 eab4b2a...5587242. Read the comment docs.

[effigies]

Looks like it works. Thanks!