[skip-changelog] Fixed links in docs. Narrowed the amount of files checked by the link-checker. (#1233)

* Fixed internal links to grpc docs

* Only check docs/*.md and various README.md for broken links

Otherwise it will check also pytest-generated READMEs and all .md files
included in unit tests data files.

* Round of go mod tidy in docsgen module

Author: cmaglie

Diff for: Taskfile.yml

@@ -65,7 +65,7 @@ tasks:
       - |
         npx -p markdown-link-check -c '
         STATUS=0
-        for file in $(find -name "*.md"); do
+        for file in $(find docs -name "*.md") README.md test/README.md client_example/README.md; do
           markdown-link-check -c markdown-link-check-config.json -q "$file"
           STATUS=$(( $STATUS + $? ))
         done

Diff for: docs/getting-started.md

@@ -350,5 +350,5 @@ metrics:
 
 [configuration documentation]: configuration.md
 [client_example]: https://github.com/arduino/arduino-cli/blob/master/client_example
-[grpc reference]: ../rpc/commands
+[grpc reference]: rpc/commands.md
 [prometheus]: https://prometheus.io/

Diff for: docs/integration-options.md

@@ -99,7 +99,7 @@ tracker] if you’ve got a use case that doesn’t fit one of the three pillars.
 [grpc]: https://grpc.io/
 [rpc]: https://en.wikipedia.org/wiki/Remote_procedure_call
 [daemon mode]: commands/arduino-cli_daemon.md
-[grpc interface reference]: ../rpc/commands
+[grpc interface reference]: rpc/commands.md
 [grpc supported languages]: https://grpc.io/docs/languages/
 [arduino cli repository]: https://github.com/arduino/arduino-cli
 [grpc client example]: https://github.com/arduino/arduino-cli/blob/master/client_example