fix: ubuntu setup install of terraform docs

[mavogel]

Current behavior

curl -s https://api.github.com/repos/terraform-docs/terraform-docs/releases/latest | grep -o -E "https://.+?-linux-amd64
# returns two urls
https://github.com/terraform-docs/terraform-docs/releases/download/v0.11.2/terraform-docs-v0.11.2-linux-amd64
https://github.com/terraform-docs/terraform-docs/releases/download/v0.11.2/terraform-docs-v0.11.2-linux-amd64
# results in the error
curl: (3) Illegal characters found in URL

Quick fix

curl -s https://api.github.com/repos/terraform-docs/terraform-docs/releases/latest | grep -o -E "https://.+?-linux-amd64" | uniq

• More suitable would be to parse the json with jq
• Or use the tar.gz URL and untar

[antonbabenko]

Fixed by #175