update BUILDING.md

BUILDING.md

@@ -28,20 +28,20 @@ base64 -i certificate.p12 -o encoded.txt
 3.  In the left sidebar, click **Secrets**.
 4.  Add the following secrets:
     1.  Certificate
-        * Name: `MAC_CERTIFICATE`
-        * Value: The encoded Base64 certificate
+        - Name: `MAC_CERTIFICATE`
+        - Value: The encoded Base64 certificate
     2.  Certificate password
-        * Name: `MAC_CERTIFICATE_PASSWORD`
-        * Value: The password that was set when the certificate was exported.
+        - Name: `MAC_CERTIFICATE_PASSWORD`
+        - Value: The password that was set when the certificate was exported.
     3.  Apple ID
-        * Name: `SIGNING_APPLE_ID`
-        * Value: The apple id (email) to use for signing
+        - Name: `SIGNING_APPLE_ID`
+        - Value: The apple id (email) to use for signing
     4.  Apple Password
-        * Name: `SIGNING_APP_PASSWORD`
-        * Value: The app-specific password that was generated for the apple id
+        - Name: `SIGNING_APP_PASSWORD`
+        - Value: The app-specific password that was generated for the apple id
     5.  Team ID (Optional)
-        * Name: `SIGNING_TEAM_ID`
-        * Value: The apple team id if you're sigining the application for a team
+        - Name: `SIGNING_TEAM_ID`
+        - Value: The apple team id if you're sigining the application for a team
 
 ## Manual
 
@@ -49,9 +49,27 @@ base64 -i certificate.p12 -o encoded.txt
 
 You will need node `10.19.0`.
 This can be done by using [nvm](https://github.com/nvm-sh/nvm) and running `nvm use` or you can install it manually.
+Once nvm is installed, just run `nvm install` to install the version from the `.nvmrc` file and then `nvm use` to use it.
 
 ### Prerequisites
 
+<details>
+<summary>Linux</summary>
+
+Here are the steps to build the app for Linux:
+
+```
+sudo apt-get install python2
+# install nvm by following their github README
+nvm install # install the current node version used in this project
+nvm use # use the current node version used in this project
+npm install -g yarn # install yarn globally for this node version
+yarn install --frozen-lockfile # install all dependecies of this project
+yarn grunt # transpile and assemble files
+yarn start-prod # start the app on production mode (currently this is the only one supported)
+```
+
+</details>
 <details>
 <summary>Windows</summary>