Documentation: Update for the removal of SERENITY_SOURCE_DIR requirement

Documentation/BuildInstructionsLadybird.md

@@ -135,9 +135,8 @@ Ladybird requires resource files from the serenity/Base/res directory in order t
 icons, fonts, and other theming information. The serenity.sh script calls into custom CMake targets
 that set these variables, and ensure that the $PWD is set properly to allow execution from the build
 directory. To run the built binary without using the script, one can either directly invoke the
-ninja rules, set $SERENITY_SOURCE_DIR to the root of their serenity checkout, or install ladybird
-using the provided CMake install rules. See the ``Custom CMake build directory`` section below for
-details.
+ninja rules or install ladybird  using the provided CMake install rules. See the ``Custom CMake build directory``
+section below for details.
 
 ### Custom CMake build directory
 
@@ -167,13 +166,11 @@ ninja -C Build/ladybird debug
 
 To run without ninja rule on non-macOS systems:
 ```
-export SERENITY_SOURCE_DIR=$(realpath ../)
 ./Build/ladybird/bin/Ladybird
 ```
 
 To run without ninja rule on macOS:
 ```
-export SERENITY_SOURCE_DIR=$(realpath ../)
 open -W --stdout $(tty) --stderr $(tty) ./Build/ladybird/bin/Ladybird.app
 
 # Or to launch with arguments:
@@ -191,7 +188,7 @@ Now breakpoints, stepping and variable inspection will work.
 ### Debugging with Xcode on macOS
 
 The `serenity.sh` build script does not know how to generate Xcode projects, so creating the project must be done manually.
-To be compatible with the script, a few extra options are required. If there is a previous Lagom build directory, CMake will likely complain that the generator has changed.
+To be compatible with the `serenity.sh` script, a few extra options are required. If there is a previous Lagom build directory, CMake will likely complain that the generator has changed.
 
 ```
 cmake -GXcode -S Meta/Lagom -B Build/lagom -DBUILD_LAGOM=ON -DENABLE_LAGOM_LADYBIRD=ON
@@ -206,12 +203,6 @@ cmake -GXcode -S Ladybird -B Build/ladybird
 After generating an Xcode project into the specified build directory, you can open `ladybird.xcodeproj` in Xcode. The project has a ton of targets, many of which are generated code.
 The only target that needs a scheme is the ladybird app bundle.
 
-In order for the application to launch properly through Xcode, the `SERENITY_SOURCE_DIR` environment variable must be set to your serenity checkout in the ladybird scheme, per the
-screenshot below. The same is true for profiling the application in Instruments. Future updates might fill out the application bundle such that the environment variable is not required.
-
-![Modify Scheme...](Xcode_ladybird_Scheme.png)
-
-
 ### Building on OpenIndiana
 
 OpenIndiana needs some extra environment variables set to make sure it finds all the executables