Update alevin.rst

doc/source/alevin.rst

@@ -191,6 +191,7 @@ A typical run of alevin will generate 4 files:
 * *quants\_tier\_mat.gz* -- Tier categorization of the matrix. 
 
 .. note:: Working with R packages
+
    Alevin generates multiple metadata files like the hash codes of the reference transcriptome and it's crucial for working with downstream R package like `tximeta <https://bioconductor.org/packages/release/bioc/html/tximeta.html>`_ . Hence along with the above files, it's advisable to keep the complete output folder generated by alevin.
 
 Along with the Cell-v-Gene count matrix, alevin dumps a 3-fold categorization of each estimated count value of a gene(each cell disjointly) in the form of tiers. Tier 1 is the set of genes where all the reads are uniquely mapping. Tier 2 is genes that have ambiguously mapping reads, but connected to unique read evidence as well, that can be used by the EM to resolve the multimapping reads. Tier 3 is the genes that have no unique evidence and the read counts are, therefore, distributed between these genes according to an uninformative prior.