Deduplicate getting started (#1613)

Summary:
## Motivation

* We shouldn't recommend installing from pip without a lot of caveats since this won't work well on OSX, as explained in the README
* It's best to not repeat information on version numbers, etc. in too many places; we should treat the README as the source of truth on installation instructions. Any install instructions other than the README should be brief and not misleading.

Pull Request resolved: #1613

Test Plan:
* Looked at the changed files in a Markdown viewer
* Built the website and looked at the changed pages:
<img width="1511" alt="image" src="https://user-images.githubusercontent.com/9137425/210680146-976d6e29-cfdb-4f18-9e23-f37d8ce842c2.png">
<img width="888" alt="image" src="https://user-images.githubusercontent.com/9137425/210680184-d2053526-1c01-4069-8b2f-4945dcf38ba2.png">

Reviewed By: Balandat

Differential Revision: D42354941

Pulled By: esantorella

fbshipit-source-id: f01e8d3d676bde7a35450b928e2de20267e544c3

Author: esantorella

docs/getting_started.md

@@ -13,20 +13,12 @@ Before jumping the gun, we recommend you start with the high-level
 
 #### Installation Requirements:
 
-- Python >= 3.8
-- PyTorch >= 1.11
-- gpytorch == 1.9.1
-- linear_operator == 0.3.0
-- scipy
-- multiple-dispatch
-- pyro-ppl >= 1.8.4
-
 BoTorch is easily installed via
-[Anaconda](https://www.anaconda.com/distribution/#download-section) (recommended)
+[Anaconda](https://www.anaconda.com/distribution/#download-section) (strongly recommended for OSX)
 or `pip`:
 
 <!--DOCUSAURUS_CODE_TABS-->
-<!--conda-->
+<!--Conda-->
 ```bash
 conda install botorch -c pytorch -c gpytorch -c conda-forge
 ```
@@ -36,7 +28,7 @@ pip install botorch
 ```
 <!--END_DOCUSAURUS_CODE_TABS-->
 
-For more detailed installation instructions, please see the
+For more installation options and detailed instructions, please see the
 [Project Readme](https://github.com/pytorch/botorch/blob/main/README.md)
 on GitHub.
 

website/pages/en/index.js

@@ -164,7 +164,7 @@ candidate  # tensor([0.4887, 0.5063])
           <ol>
             <li>
               <h4>Install BoTorch:</h4>
-              <a>via conda (recommended):</a>
+              <a>via Conda (strongly recommended for OSX):</a>
               <MarkdownBlock>{bash`conda install botorch -c pytorch -c gpytorch -c conda-forge`}</MarkdownBlock>
               <a>via pip:</a>
               <MarkdownBlock>{bash`pip install botorch`}</MarkdownBlock>