Update documentation to reflect missing eth.getCompilers

[cowlicks]

System information

Geth version: 1.8.13 stable
OS & Version: linux 4.17.13-arch

Expected behaviour

The example in the official contract tutorial documentation (link) should work.

Actual behaviour

It does not because it references an outdated API: eth.getCompilers, admin.setSolc, etc.

There are related issues about these API's being gone #3793 #2598. This is an issue about documentation which should be match the current behavior.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.