Docs: Add mention to install devDependencies

Before `yarn build` can be succesfully run, we need to install the devDependencies.
This is necessary, because `bin/setup` does not install the devDependencies…

Signed-off-by: Philip Molares <philip.molares@udo.edu>

2 files changed, 3 insertions, 3 deletions

diff --git a/bin/setup b/bin/setup
index b4a7ae9d..907567ca 100755
--- a/bin/setup
+++ b/bin/setup
@@ -50,7 +50,7 @@ echo "Installing packages..."
 yarn install --production=true --pure-lockfile
 
 cat << EOF
-
+If you want to build the frontend yourself, you need to run 'yarn install' before 'yarn build' to install the devDependencies for the build process.
 
 Edit the following config file to setup HedgeDoc server and client.
 Read more info at https://docs.hedgedoc.org/configuration/
diff --git a/docs/content/setup/manual-setup.md b/docs/content/setup/manual-setup.md
index bbd73f79..f3ce3702 100644
--- a/docs/content/setup/manual-setup.md
+++ b/docs/content/setup/manual-setup.md
@@ -34,7 +34,7 @@
    It's also possible to use environment variables.
    For details, have a look at [the configuration documentation](../configuration.md).
 5. *:octicons-light-bulb-16: If you use the release tarball for 1.7.0 or newer, this step can be skipped.*  
-   Build the frontend bundle by running `yarn run build`.
+   Build the frontend bundle by running `yarn install` and then `yarn build`. The extra `yarn install` is necessary as `bin/setup` does not install the build dependencies.
 6. It is recommended to start your server manually once:  
    ```shell
    NODE_ENV=production yarn start
@@ -61,7 +61,7 @@ If you want to upgrade HedgeDoc from an older version, follow these steps:
    <small>If you use Git, you can check out the new tag with e.g. `git fetch origin && git checkout 1.8.1`</small>
 5. Run `bin/setup`. This will take care of installing dependencies. It is safe to run on an existing installation.
 6. *:octicons-light-bulb-16: If you used the release tarball for 1.7.0 or newer, this step can be skipped.*  
-   Build the frontend bundle by running `yarn run build`.
+   Build the frontend bundle by running `yarn install` and `yarn build`. The extra `yarn install` is necessary as `bin/setup` does not install the       build dependencies.
 7. It is recommended to start your server manually once:
    ```shell
    NODE_ENV=production yarn start