add documentation for Generic Validation

Author: mmusich

Alignment/OfflineValidation/README.md

@@ -117,5 +117,11 @@ For details read [`README_JetHT.md`](https://github.com/cms-sw/cmssw/blob/master
 ## MTS validation
 For details read [`README_MTS.md`](https://github.com/cms-sw/cmssw/blob/master/Alignment/OfflineValidation/README_MTS.md)
 
+## Pixel BaryCenter
+For details read [`README_MTS.md`](https://github.com/cms-sw/cmssw/blob/master/Alignment/OfflineValidation/README_PixBary.md)
+
+## Generic validation (dataset validation)
+For details read [`README_Generic.md`](https://github.com/cms-sw/cmssw/blob/master/Alignment/OfflineValidation/README_Generic.md)
+
 ## General info about IOV/run arguments
 For details read [`README_IOV.md`](https://github.com/cms-sw/cmssw/blob/master/Alignment/OfflineValidation/README_IOV.md)

Alignment/OfflineValidation/README_Generic.md

@@ -0,0 +1,39 @@
+# Generic Validation
+
+## General info
+```
+validations:
+    Generic:
+        <step_type>:
+            <step_name>: 
+                <options>
+```
+
+Generic validation runs in 2 possible types of steps:
+ - single (validation analysis by GenericV_cfg.py)
+ - (optional) merge (GenericVmerge macro)
+Step name is and arbitrary string which will be used as a reference for consequent steps.
+Merge job awill only start if all corresponding single jobs are done.
+Merge jobs can run in parallel.
+
+## Single Generic jobs
+Single jobs can be specified per run (IoV as well). In case of MC, IoV is specified to arbitrary 1.  
+
+Variable | Default value | Explanation/Options
+-------- | ------------- | --------------------
+IOV | None | List of IOVs/runs defined by integer value. IOV 1 is reserved for MC.
+Alignments | None | List of alignments. Will create separate directory for each.
+dataset | See defaultInputFiles_cff.py | Path to txt file containing list of datasets to be used. If file is missing at EOS or is corrupted - job will eventually fail (most common issue).
+goodlumi | cms.untracked.VLuminosityBlockRange() | Path to json file containing lumi information about selected IoV - must contain list of runs under particular IoV with lumiblock info. Format: `IOV_Vali_{}.json`
+maxevents | 1 | Maximum number of events before cmsRun terminates.
+trackcollection | "generalTracks" | Track collection to be specified here, e.g. "ALCARECOTkAlMuonIsolated" or "ALCARECOTkAlMinBias" ... 
+tthrbuilder | "WithAngleAndTemplate" | Specify TTRH Builder
+
+## Merge Generic job
+Its name do not need to match single job name but option `singles` must list all single jobs to be merged.
+Generic merged plot style can be adjusted from global plotting style.
+
+Variable | Default value | Explanation/Options
+-------- | ------------- | --------------------
+singles | None | List of strings matching single job names to be merged in one plot.
+customrighttitle | "" | Top right title. Reserved word "IOV" will be replaced for given IOV/run in the list.