[Reachability] Scan summary and better docs

[meghfossa]

Overview

This PR,

• Adds scan summary for reachability analysis
• Adds better docs for reachability, and moves reachability docs in better location

Acceptance criteria

• Scan summary is displayed for reachability

Testing plan

git checkout feat/better-docs && make install-dev

git clone https://github.com/fossas/reachability-with-maven-example.git
cd reachability-with-maven-example

# (required) perform maven build
# if jar artifact is not present reachability will not be performed
mvn package

# Analyze with fossa-dev
fossa-dev analyze -p reachability-example-better-docs -r example-revision --fossa-api-key <MY-FOSSA-KEY>

• You should see the scan summary in stdout.
• You should see OrgId does not support reachability message, if your org does not support reachability

Risks

N/A

Metrics

N/A

References

https://fossa.atlassian.net/browse/ANE-1416

• I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• If this PR introduced a user-visible change, I added documentation into docs/.
• If this PR added docs, I added links as appropriate to the user manual's ToC in docs/README.ms and gave consideration to how discoverable or not my documentation is.
• If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an # Unreleased section at the top.
• If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json AND I have updated example files used by fossa init command. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).
• If I made changes to a subcommand's options, I updated docs/references/subcommands/<subcommand>.md.

[meghfossa]

To avoid circular imports