Add language version to Dependency Scanning docs

Problem to solve

The purpose of this issue is to update the Supported languages and package managers table to include a new column "Language Version", which will document the supported versions for each language. For example, Java will have supported language versions 8, 11, 13, 14, 15, 16.

Further details

Please see this comment for background info

Implementation Plan

Please see this Draft MR as a starting point

1. Add a new Language Versions column, with N/A for every entry except Java, which shows 8, 11, 13, 14, 15, 16

2. Remove Package Manager Versions column from the Supported languages and package managers table.

3. Add two new tables:

   • Obtaining dependency information by parsing lockfiles with headings:
     • Package Manager
     • Supported File Format Versions
     • Tested Versions
   • Obtaining dependency information by running a package manager to generate a parsable file with headings:
     • Package Manager
     • Preinstalled Versions
     • Tested Versions

4. Add superscripts for certain elements of the tables, for example, the entry for bundler will have a superscript which links to a note explaining:

   The installed version of bundler is only used for the bundler-audit analyzer, and is not used for gemnasium

See here for previous implementation plan

1. [ ] Add new `Language Versions` column, with `N/A` for every entry _except_ `Java`, which shows `8, 11, 13, 14, 15, 16` 1. [ ] Add current version of `Package Manager` to the `Package Manager Versions` column 1. [ ] In the Notes regarding supported languages and package managers section underneath the table, add text similar to the following:

Package managers and language versions listed are those that we currently have automated test coverage for, however, versions not listed might be supported. If you come across a package manager or language version which is not supported, please create a new issue to request support.

/cc @gonzoyumo @NicoleSchwartz