Remove '$' in code snippets

[sigalsax]

What does this PR do?

This commit removes the '$' from the code snippets in our docs in response to GHs rollout of the clipboard feature. If those '$' signs remain and a user clicks on the clipboard to copy the command, the '$' will be copied as well.

What ticket does this PR close?

Resolves #-

Checklists

Change log

• [ ] The CHANGELOG has been updated, or
• [x] This PR does not include user-facing changes and doesn't require a CHANGELOG update

Test coverage

• [ ] This PR includes new unit and integration tests to go with the code changes, or
• [x] The changes in this PR do not require tests

Documentation

• [ ] Docs (e.g. READMEs) were updated in this PR, and/or there is a follow-on issue to update docs, or
• [x] This PR does not require updating any documentation

[codeclimate[bot]]

Code Climate has analyzed commit ffd5c274 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (75% is the threshold).

This pull request will bring the total coverage in the repository to 89.7% (0.0% change).

View more on Code Climate.