[no ci] docs: remove $ prefix from v1 install command

Author: vpratz

README.md

@@ -267,7 +267,7 @@ accessed by selecting the "stable-legacy" entry in the version picker of the doc
 You can also install the latest version of BayesFlow v1.x from PyPI using
 
 ```
-$ pip install "bayesflow<2.0"
+pip install "bayesflow<2.0"
 ```
 
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