Add support section and fix CI action

.github/workflows/go.yml

@@ -23,10 +23,10 @@ jobs:
       PDFIUM_EXPERIMENTAL_GO_VERSION: "1.21"
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Set up Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
           go-version: ${{ matrix.go }}
       - name: Set up PDFium library (Linux)
@@ -82,29 +82,29 @@ jobs:
           go test -timeout 30m ./internal/implementation_cgo ./internal/implementation_webassembly -coverprofile=coverage.out -covermode=atomic -tags pdfium_experimental -v
       - name: Archive code coverage results
         if: matrix.os == 'ubuntu-latest' && matrix.go == env.PDFIUM_EXPERIMENTAL_GO_VERSION && matrix.pdfium == env.PDFIUM_EXPERIMENTAL_VERSION
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v3
         with:
           name: code-coverage-report
           path: ./coverage.out
       - name: Upload coverage to Codecov
         if: matrix.os == 'ubuntu-latest' && matrix.go == env.PDFIUM_EXPERIMENTAL_GO_VERSION && matrix.pdfium == env.PDFIUM_EXPERIMENTAL_VERSION
-        uses: codecov/codecov-action@v2
+        uses: codecov/codecov-action@v3
         with:
           files: coverage.out
   test-webassembly:
     strategy:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
-        go: [ "1.18", "1.19", "1.20" ]
+        go: [ "1.19", "1.20", "1.21" ]
     env:
-      PDFIUM_EXPERIMENTAL_GO_VERSION: "1.20"
+      PDFIUM_EXPERIMENTAL_GO_VERSION: "1.21"
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Set up Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
           go-version: ${{ matrix.go }}
       - name: Test all packages

README.md

@@ -655,6 +655,26 @@ single-threaded or WebAssembly usage. It's not possible to encode the `io.Writer
 processes for that
 matter.
 
+## Support Policy
+
+We offer an API stability promise with semantic versioning. In other words, we
+promise to not break any exported function signature without incrementing the
+major version. New features and behaviors happen with a minor version
+increment, e.g. 1.0.11 to 1.1.0. We also fix bugs or change internal details
+with a patch version, e.g. 1.0.0 to 1.0.1. Upgrades of the supported PDFium
+version will cause a minor version update
+
+### Go
+
+This project will support the last 3 version of Go, this means that if the last
+version of Go is 1.21, our `go.mod` will be set to Go 1.19, and our CI tests
+will be run on Go 1.19, 1.20 and 1.21. It won't mean that the library won't
+work with older versions of Go, but it will tell you what to expect of the
+supported  Go versions. If we change the supported Go versions, we will make
+that a minor version upgrade. This policy allows you to not be forced to the
+latest Go version for a pretty long time, but it still allows us to use new 
+language features in a pretty reasonable time-frame.
+
 ## About Klippa
 
 Founded in 2015, [Klippa](https://www.klippa.com/en)'s goal is to digitize & automate administrative processes with