Updated Building for macOS (markdown)

Building-for-macOS.md

@@ -103,4 +103,69 @@ cd ./dolphin-emu
 git pull origin
 cd build
 cmake .. && make
+```
+
+### FAQ
+## When building Dolphin, I get errors
+If you are receiving this error:
+```
+CMake Error at Source/Core/DolphinQt/CMakeLists.txt:9 (find_package):
+  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "Qt5", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "Qt5" (requested
+  version 5.9) with any of the following names:
+
+    Qt5Config.cmake
+    qt5-config.cmake
+
+  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
+  to a directory containing one of the above files.  If "Qt5" provides a
+  separate development package or SDK, be sure it has been installed.
+```
+
+# Solution 1
+If you have [Homebrew](https://brew.sh/) installed, and you installed QT5 from there, uninstall Homebrew QT5 using this command:
+
+```bash
+brew uninstall qt5
+```
+
+Then, download the offline installer from [qt.io/offline-installers](https://www.qt.io/offline-installers), run the installer inside the DMG file and log in or sign up to/for a `QT Account`.
+
+On the `Installation Folder` step, select your home folder.
+
+![Your local Home Directory](https://user-images.githubusercontent.com/69256931/159339892-cdf065b6-3f6f-48ac-848f-071dc853e376.png)
+
+Then, on the `Select Components` page, expand the `Qt x.x.x` section and check the box next to `macOS`.
+
+![Box selection](https://user-images.githubusercontent.com/69256931/159340196-6a405d7e-8f88-4d7f-b06f-1ae40f39a2a7.png)
+
+After that, click `Next`, agree to the license(s), click `Next` again then finally, after all that time...
+
+Click `Install`.
+
+After it has finished installing, follow these steps:
+
+Export your Qt5_DIR to the folder in your Qt installation with Qt5Config.cmake in it. In this case, it should be:
+```bash
+export Qt5_DIR=~/Qtx.x.x
+```
+
+(Replacing the `x`'s with the version numbers)
+
+Append the Qt5_DIR to your PATH with `export PATH=$PATH:$Qt5_DIR`
+
+And then...
+`echo "export Qt5_DIR=$Qt5_DIR" >> ~/.bash_profile`
+`echo 'export PATH=$PATH:$Qt5_DIR' >> ~/.bash_profile`
+
+Now, we can build with CMake (make sure to `cd` into the Dolphin source folder!):
+
+```bash
+mkdir -p build
+cd build
+cmake ..
+make
 ```