fix mkdocs doc paths

[DavidMinarsch]

Proposed changes

Fix paths

Fixes

If it fixes a bug or resolves a feature request, be sure to link to that issue.

Types of changes

What types of changes does your code introduce to agents-aea?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• I am making a pull request against the develop branch (left side). Also you should start your branch off our develop.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have checked that code coverage does not decrease.
• I have checked that the documentation about the aea cli tool works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

DELETE INCLUSIVE THIS AND BELOW FOR STANDARD PR

Release summary

Version number: [e.g. 1.0.1]

Release details

Describe in short the main changes with the new release.

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• I am making a pull request against the master branch (left side), from develop
• Lint and unit tests pass locally
• I have checked the fingerprint hashes are correct by running (scripts/generate_ipfs_hashes.py)
• I have regenerated the latest API docs
• I built the documentation and updated it with the latest changes
• I have added an item in HISTORY.md for this release
• I bumped the version number in the aea/__version__.py file.
• I bumped the version number in the docs/version.md file
• I bumped the version number in every Docker image of the repo and published it. Also, I built and published them with tag latest
  (check the READMEs of aea-develop
  and aea-deploy)
• I have checked that the documentation about the aea cli tool works
• I have pushed the latest packages to the registry.

Further comments

Write here any other comment about the release, if any.