Correct formatting errors in Encodings.md

[BMDan]

In particular, address the issue that formatting caused the text after "The data stream looks like:" in "Delta-length byte array" to disappear entirely.

The remainder of changes are simply for consistency and readability.

Make sure you have checked all steps below.

Jira

• [ ] My PR addresses the following Parquet Jira issues and references them in the PR title. For example, "PARQUET-1234: My Parquet PR"
  • https://issues.apache.org/jira/browse/PARQUET-XXX
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Commits

• [ ] My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• [ ] In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain Javadoc that explain what it does

[BMDan]

Tagging @jincongho ; is it worth creating a Jira issue for this, or should I just close the PR?

[jincongho]

@BMDan Go ahead to create a Jira issue; though I dont have permission to help you merge PR.