…ostgres-plr#111

Note
```
[skip ci] appearing in the "extended description": ignored by Appveyor, read by Github Actions
```
Therefore, this pull request will build on Appveyor.

Appveyor - *.md
https://www.appveyor.com/docs/how-to/filtering-commits/
```
Commit files (GitHub and Bitbucket only)
Skip commits . . .
skip_commits.files allows skipping AppVeyor build
if all of the files modified in push’s head commit match any of the file matching rules.
```

Travis - *.md
https://reflectoring.io/skip-ci-build/
```
script for Travis CI on GitHub and modified it
creates a diff of all commits and exits the build if it only includes markdown files
```
Note, I could not test travis.org.
I am not allowed to add branches.
Travis.org claims to shut down before the end of May.

Github Actions - *.md
https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions
```
paths-ignore . . .
When using the push and pull_request events,
you can, configure a workflow to run, when at least one file does not match
paths-ignore, or at least one modified file matches the configured paths.

```
Github Actions - [skip actions]
This custom solution is not restricted by "web hook event payload" ("push", "pull_request")
https://dev.to/epassaro/use-skip-ci-in-github-actions-1mnf
```
If you want to just check the latest commit, change it to:
```
```
if: "!contains(github.event.head_commit.message, '[ci skip]')"
```

Summary of directly asking to skip the build
 * Appveyor                - [skip ci], [skip appveyor]
 * Github Actions (custom) - [skip ci], [skip actions], [skip github actions]
 * Travis                  - [skip ci], [skip travis]

Tested at . .
https://github.com/AndreMikulec/plr/tree/master_no_run_skip_ci_or_only_change_in_md_dev
(eventually) non-runs (ignored runs) at . . .
https://ci.appveyor.com/project/AndreMikulec/plr/history
and (eventually) non-runs (ignored runs) at . . .
https://github.com/AndreMikulec/plr/actions?query=branch%3Amaster_no_run_skip_ci_or_only_change_in_md_dev

Issue Fix postgres-plr#111