docs: setup Sphinx build on Ubuntu

.github/workflows/cmake.yml

@@ -26,6 +26,9 @@ jobs:
     - name: Linux Build
       if: runner.os == 'Linux'
       run: |
+          sudo apt-get update
+          # for Sphinx
+          sudo apt-get install -y python3-pip
           ./build-linux-64.sh
 
     - name: macOS Build

README.md

@@ -45,7 +45,10 @@ Dependencies: Embree 3.0+, TBB (TODO: version?), Sphinx (for building manuals)
 ### Ubuntu
 
 ```
-sudo apt install libembree-dev libtbb-dev python3-sphinx cmake build-essential g++
+sudo apt install libembree-dev libtbb-dev cmake build-essential g++
+sudo apt install python3-pip
+python3 -m pip install sphinx_rtd_theme
+export PATH="~/.local/bin/:$PATH"
 git clone --recursive https://github.com/ericwa/ericw-tools
 cd ericw-tools
 mkdir build

build-linux-64.sh

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+python3 -m pip install sphinx_rtd_theme
+export PATH="~/.local/bin/:$PATH"
+
 BUILD_DIR=build-linux
 
 if [ -d "$BUILD_DIR" ]; then