Update README.md

[rishitb-mongodb]

Added mention of Semantic Versioning to the README.md file. Addresses DRIVERS-3015.

[stIncMale]

• We produce more libraries than just the drivers from this repository, and there is no reason to list them all here in the "Versioning" section.
• We try to follow semantic versioning, but I don't believe we have never violated it, or guarantee that we will never violate it.

Let's rephrase to something like

Suggested change

	The MongoDB Java, Kotlin and Scala drivers follow [semantic versioning](https://semver.org/) for their releases.
	We generally follow [semantic versioning(https://semver.org/) when releasing.

[katcharov]

@rishitb-mongodb @stIncMale Note that the ticket says:

This will help foster confidence that we do strictly follow semantic versioning even though it might be obvious from our past releases.

[stIncMale]

1. In that case, let's use the option B suggested in the ticket, specifying 5.6.0 as the "since" version. And say that historically the driver generally followed semantic versioning, but may not always had followed it strictly. I vaguely remember us talking about some changes technically requiring a more severe version change, but deciding not to do that.
   1.1. We also should remove all the text from the "Versioning" section of the readme, leaving there only the information about us following semantic versioning. Having that text will only introduce confusion, unless the text is identical to the semantic versioning specification.
   1.2. Semantic versioning specification itself has versions, and since the intent is to promise that we'll follow it strictly, we should specify the semantic versioning version and link to it (https://semver.org/spec/v2.0.0.html), instead of vaguely referring to semantic versioning as an idea. DRIVERS-3105 fails to require this, but I don't think is possible to talk about strict strict compliance without specifying the spec version being complied with.
   1.3. I guess, we'll have to be much more careful with releases, and carefully read all the rules of the versioning scheme.
2. The suggestion about not listing all the libraries we produce from this codebase is still relevant.

[jyemin]

I think we can safely say that we've been strictly following semantic versioning since at least the 3.0 release.