Update docs pointing to the new CMSSW for el9

docs/index.md

@@ -27,7 +27,28 @@ should be sufficient. To choose a release version, you can find the latest
 releases on github under
 [https://github.com/cms-analysis/HiggsAnalysis-CombinedLimit/releases](https://github.com/cms-analysis/HiggsAnalysis-CombinedLimit/releases)
 
-### Combine v9 - recommended version
+### Combine v10 - recommended version
+
+The nominal installation method is inside CMSSW. The current release targets
+the CMSSW `14_0_X` series because of the recent switch to el9 at lxplus machines.
+
+
+```sh
+cmsrel CMSSW_14_0_0_pre1
+cd CMSSW_14_0_0_pre1/src
+cmsenv
+git clone https://github.com/cms-analysis/HiggsAnalysis-CombinedLimit.git HiggsAnalysis/CombinedLimit
+cd HiggsAnalysis/CombinedLimit
+```
+Update to a recommended tag - currently the recommended tag is **v10.0.0**: [see release notes](https://github.com/cms-analysis/HiggsAnalysis-CombinedLimit/releases/tag/v9.1.0)
+
+```sh
+cd $CMSSW_BASE/src/HiggsAnalysis/CombinedLimit
+git fetch origin
+git checkout v10.0.0
+scramv1 b clean; scramv1 b # always make a clean build
+```
+### Combine v9 
 
 The nominal installation method is inside CMSSW. The current release targets
 the CMSSW `11_3_X` series because this release has both python2 and python3 ROOT