Add firefox installation from src instructions (#1371)

* Add firefox installation from src instructions

* Update build script for src code

* add corepack enable

* Add corepack enable to docs for dev

.github/workflows/pr-any.yml

@@ -15,5 +15,6 @@ jobs:
         node-version: 'lts/*'
     - name: ${{ matrix.step }}
       run: |
+        corepack enable
         yarn install --immutable
         yarn ${{ matrix.step }}

.github/workflows/push-master.yml

@@ -27,5 +27,6 @@ jobs:
         GH_RELEASE_FILES: master-build.zip,master-src.zip
         NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
       run: |
+        corepack enable
         yarn install --immutable
         yarn ${{ matrix.step }}