[Docs] Recommend .upToNextMinor before we tag 1.0 (#7)

[Docs] Recommend .upToNextMinor before we tag 1.0

### Motivation

In our detailed docs, we do recommend adopters use `.upToNextMinor(from: "...")` before we tag 1.0, but our README and getting started docs still used `from` (aka `.upToNextMajor`).

### Modifications

Updated the docs to use `.upToNextMinor`

### Result

Now adopters should use that recommendation and only upgrade between minor versions manually.

### Test Plan

Previewed locally, looks good.


Reviewed by: simonjbeaumont, simonjbeaumont

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#7

Author: czechboy0

README.md

@@ -13,10 +13,15 @@ It contains:
 Add the package dependency in your `Package.swift`:
 
 ```swift
-.package(url: "https://github.com/apple/swift-openapi-runtime", from: "0.1.0"),
+.package(
+    url: "https://github.com/apple/swift-openapi-runtime",
+    .upToNextMinor(from: "0.1.0")
+),
 ```
 
-and in your target, add `OpenAPIRuntime` to your dependencies:
+Note that this repository does not have a 1.0 tag yet, so the API is not stable.
+
+Next, in your target, add `OpenAPIRuntime` to your dependencies:
 
 ```swift
 .target(name: "MyTarget", dependencies: [

Sources/OpenAPIRuntime/Documentation.docc/Documentation.md

@@ -15,10 +15,15 @@ It contains:
 Add the package dependency in your `Package.swift`:
 
 ```swift
-.package(url: "https://github.com/apple/swift-openapi-runtime", from: "0.1.0"),
+.package(
+    url: "https://github.com/apple/swift-openapi-runtime",
+    .upToNextMinor(from: "0.1.0")
+),
 ```
 
-and in your target, add `OpenAPIRuntime` to your dependencies:
+Note that this repository does not have a 1.0 tag yet, so the API is not stable.
+
+Next, in your target, add `OpenAPIRuntime` to your dependencies:
 
 ```swift
 .target(name: "MyTarget", dependencies: [