add installation notes for CUDA 12.4, pyenv, and PyTorch; include useful links

notes/pyenv-install.md

@@ -0,0 +1,46 @@
+# pyenv install
+
+## install
+
+nice to have:
+
+```bash
+sudo apt install python-is-python3
+```
+
+```bash
+curl https://pyenv.run | bash
+```
+
+## setup zsh
+
+add the following to `.zshrc`:
+
+```bash
+export PYENV_ROOT="$HOME/.pyenv"
+[[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PATH"
+eval "$(pyenv init -)"
+```
+
+## pyenv install
+
+prerequisites:
+
+```bash
+sudo apt update
+sudo apt install build-essential libssl-dev zlib1g-dev \
+libbz2-dev libreadline-dev libsqlite3-dev curl git \
+libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev \
+libffi-dev liblzma-dev python3-pip
+```
+
+install:
+
+```bash
+# using python 3.12.7 as an example
+pyenv install 3.12.7
+
+# optional
+pyenv global 3.12.7
+pyenv versions
+```