docs: Update COLLABORATOR_GUIDE.md and CONTRIBUTING.md to include label meanings (#4874)

Add label meanings for collaborators to know when to put labels and to let contributors know what labels mean when they are applied.

COLLABORATOR_GUIDE.md

@@ -3,6 +3,7 @@
 ## Table of Contents
 
 * [Issues and Pull Requests](#issues-and-pull-requests)
+  * [Labels](#labels)
 * [Accepting changes](#accepting-changes)
   * [Involving the TSC](#involving-the-tsc)
 * [Landing a PR](#landing-a-pr)
@@ -30,6 +31,23 @@ Any issue and PR can be closed if they are not relevant, when in doubt leave it
 
 If issues or PRs are very short and don't contain much information, ask for more by linking to the [issue][issue template] or [PR][pr template] template. There is also a [response guide](https://github.com/videojs/video.js/wiki/New-Issue-Response-Guide) if you're unsure.
 
+### Labels
+
+There are labels that are useful to include on issues and PRs. A few of them are defined below:
+
+| Label | Issue or PR | Description |
+|-------|-------------|-------------|
+| confirmed | Issue and PR | Issue: marks as reproducible. PR: marks as ready to be merged|
+| 5.x | PR | Marks as a change to the 5.x branch only |
+| bug | Issue | Marks as a confirmed bug |
+| good first issue | Issue | Marks as a good bug or enhancement for first time contributors to Video.js |
+| first-timers-only | Issue | Marks as a good bug or enhancement to be done by a newcomer to open source |
+| minor, patch, major | PR | Marks PR with the expected semver classification of the change |
+| needs: LGTM | PR | Marks PR to be reviewed by a collaborator |
+| needs: more info | Issue | Marks as needing more information from the issue reporter |
+| needs: reduced test case | Issue | Marks as needing a reduced test case from the issue reporter |
+
+
 ## Accepting changes
 
 Any code change in video.js should be happening through Pull Requests on GitHub. This includes core committers.

CONTRIBUTING.md

@@ -8,6 +8,7 @@ So you want to help out? Great! There's a number of ways you can get involved.
 * [Filing issues](#filing-issues)
   * [Reporting a Bug](#reporting-a-bug)
   * [Requesting a Feature](#requesting-a-feature)
+  * [Labels](#labels)
 * [Contributing code](#contributing-code)
   * [Building video.js locally](#building-videojs-locally)
     * [Forking and cloning the repository](#forking-and-cloning-the-repository)
@@ -74,6 +75,21 @@ A good bug report should be as detailed as possible, so that others won't have t
 
 **[Request a feature](https://github.com/videojs/video.js/issues/new)**
 
+### Labels
+
+There are a few labels that might be added to your issue or PR by a maintainer. Here's a quick rundown of what they mean:
+
+| Label | Issue or PR | Description |
+|-------|-------------|-------------|
+| confirmed | Issue and PR | Issue: marks as reproducible by a maintainer. PR: marked by a maintainer as ready to be merged|
+| 5.x | PR | Marks as a change to the 5.x branch only |
+| bug | Issue | Marks as a confirmed bug by a maintainer |
+| good first issue | Issue | Marked as a good bug or enhancement for first time contributors to Video.js |
+| first-timers-only | Issue | Marked as a good bug or enhancement to be done by a newcomer to open source |
+| minor, patch, major | PR | Marks PR with the expected [semver](https://semver.org/) classification of the change |
+| needs: more info | Issue | Marked by a maintainer as needing more information from the issue reporter. Please update your issue with more information to help us reproduce the bug. |
+| needs: reduced test case | Issue | Marked by a maintainer as needing a reduced test case from the issue reporter. Please create a test page that we can inspect to help us indentify a bug. |
+
 ## Contributing code
 
 To contibute code you'll need to be able to build a copy of Video.js and run tests locally. There are a few requirements before getting started.