Add instructions to easily install specific versions on faq.md (#4084)

* Added instructions to easily install specific versions on faq.md

* Small typo

* Moved instructions on how to install specific version to linux.md

* Update docs/linux.md

* Update docs/linux.md

---------
Co-authored-by: Jeffrey Morgan <jmorganca@gmail.com>

docs/linux.md

@@ -100,6 +100,16 @@ sudo curl -L https://ollama.com/download/ollama-linux-amd64 -o /usr/bin/ollama
 sudo chmod +x /usr/bin/ollama
 ```
 
+## Installing specific versions
+
+Use `OLLAMA_VERSION` environment variable with the install script to install a specific version of Ollama, including pre-releases. You can find the version numbers in the [releases page](https://github.com/ollama/ollama/releases). 
+
+For example:
+
+```
+curl -fsSL https://ollama.com/install.sh | OLLAMA_VERSION=0.1.32 sh
+```
+
 ## Viewing logs
 
 To view logs of Ollama running as a startup service, run: