Doc: cross-reference Emscripten version number locations

.github/workflows/ci-emscripten.yml

@@ -12,7 +12,8 @@ jobs:
 
     runs-on: ubuntu-latest
     container:
-      # If you change this version, change the number in the cache step too.
+      # If you change this version, change the numbers in the cache step,
+      # .github/workflows/preview-build.yml (2x) and os/emscripten/Dockerfile too.
       image: emscripten/emsdk:3.1.57
 
     steps:
@@ -33,6 +34,8 @@ jobs:
     - name: Setup cache
       uses: actions/cache@v4
       with:
+        # If you change this version, change the numbers in the image configuration step,
+        # .github/workflows/preview-build.yml (2x) and os/emscripten/Dockerfile too.
         path: /emsdk/upstream/emscripten/cache
         key: 3.1.57-${{ runner.os }}
 

.github/workflows/preview-build.yml

@@ -20,7 +20,8 @@ jobs:
 
     runs-on: ubuntu-latest
     container:
-      # If you change this version, change the number in the cache step too.
+      # If you change this version, change the numbers in the cache step,
+      # .github/workflows/ci-emscripten.yml (2x) and os/emscripten/Dockerfile too.
       image: emscripten/emsdk:3.1.57
 
     steps:
@@ -38,6 +39,8 @@ jobs:
       uses: actions/cache@v4
       with:
         path: /emsdk/upstream/emscripten/cache
+        # If you change this version, change the numbers in the image configuration step,
+        # .github/workflows/ci-emscripten.yml (2x) and os/emscripten/Dockerfile too.
         key: 3.1.57-${{ runner.os }}
 
     - name: Add liblzma support

os/emscripten/Dockerfile

@@ -1,3 +1,5 @@
+# If you change this version, change the numbers in .github/workflows/ci-emscripten.yml (2x)
+# and .github/workflows/preview-build.yml (2x) too.
 FROM emscripten/emsdk:3.1.57
 
 RUN apt-get update \