[Docs] Update the generator minimum version (#68)

Author: czechboy0

README.md

@@ -40,7 +40,7 @@ The generated code, runtime library, and transports are supported on more platfo
 
 | Component | macOS | Linux | iOS | tvOS | watchOS |
 | -: | :-: | :-: | :-: | :-: | :-: |
-| Generator plugin and CLI            | ✅ 13+  | ✅     | ❌     | ❌     | ❌    |
+| Generator plugin and CLI            | ✅ 10.15+  | ✅     | ❌     | ❌     | ❌    |
 | Generated code, runtime, transports | ✅ 10.15+  | ✅     | ✅ 13+ | ✅ 13+ | ✅ 6+ |
 
 ## Documentation

Sources/swift-openapi-generator/Documentation.docc/Swift-OpenAPI-Generator.md

@@ -52,7 +52,7 @@ The generated code, runtime library, and transports are supported on more platfo
 
 | Component | macOS | Linux | iOS | tvOS | watchOS |
 | -: | :-: | :-: | :-: | :-: | :-: |
-| Generator plugin and CLI            | ✅ 13+  | ✅     | ❌     | ❌     | ❌    |
+| Generator plugin and CLI            | ✅ 10.15+  | ✅     | ❌     | ❌     | ❌    |
 | Generated code, runtime, transports | ✅ 10.15+  | ✅     | ✅ 13+ | ✅ 13+ | ✅ 6+ |
 
 ## Topics