[Website] update links from absolute to relative in md files

[bullet03]

• update links from absolute path to relative one in md files

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[bullet03]

R: @aromanenko-dev, coould you, please help with review?

[github-actions]

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[aromanenko-dev]

@bullet03 Is it expected behaviour that it add index.html for relative links (e.g. see an attached screenshot)? I didn't notice the same behaviour for absolute links as it was before?
Also, if I drop index.html from the URL in browser, it got broken.

[aromanenko-dev]

Please, check if the old style links (without index.html in the end) are still working

[bullet03]

@bullet03 Is it expected behaviour that it add index.html for relative links (e.g. see an attached screenshot)? I didn't notice the same behaviour for absolute links as it was before? Also, if I drop index.html from the URL in browser, it got broken.

Had a consultation with devops from apache-beam. index.html is added to the end of the files in staging automatically. Links don't work without this part at the end only on staging. It worked like this before: here are some examples with staging from different PRs, one from December and another one from February. index.html part was present.

[bullet03]

Please, check if the old style links (without index.html in the end) are still working

Since the path is relative, index.html in the end won't affect localhost or prod, just only staging.
For instance path like /get-started/try-beam-playground/ will lead to localhost:1313/get-started/try-beam-playground on localhost, to https://beam.apache.org/get-started/try-beam-playground on production and to http://apache-beam-website-pull-requests.storage.googleapis.com/24427/get-started/try-beam-playground/index.html on staging.

Right now there are absolute links like https://beam.apache.org/get-started/try-beam-playground on both of 3 environments. If I click on such a link on localhost, I won't get to another localhost page, but to production site instead.

[aromanenko-dev]

@bullet03 Thanks for verification! It would be great to have the same behaviour everywhere - locally, on staging and on production - for the future, if it's possible, of course, to avoid such confusion.

LGTM expecting that it just drops https://beam.apache.org/ from absolute website links.