Add rvagg as a member to "githut-mgmt stewards"

Also started documented why the current set of members are there.

This is being done now because there have been various permissions/access issues of late as part of cleaning up repos that FilOz owns/maintainers (e.g., improving CI, updating dependencies, adding dependabot).
This set of members will also get reviewed and improved as part of #47

github/filecoin-project.yml

@@ -5231,10 +5231,29 @@ teams:
       # ATTN: members are expected to:
       #  - be familiar with GitHub Management
       #  - be ready to triage/review org configuration change request in github-mgmt
-      maintainer:
-        - galargh
       member:
+        # Why @BigLep?
+        # 1. This can be temporarily, but at least of 2024-08-02, he is a FilOz team member getting github-mgmt setup and operationalized
+        #    (e.g., https://github.com/filecoin-project/community/discussions/710).
+        # 2. He has experience working with github-mgmt in other contexts (e.g., ipfs per https://github.com/ipfs/ipfs/issues/511)
         - BigLep
+        # Why @galargh?
+        # 1. He has deep knowledge of the tool and its use as the creator.
+        # 2. He is co-founder of IPDX, which has a contract in 2024 to support developer productivity in the filecoin-project ecosystem.
+        - galargh
+        # Why @jennijuju?
+        # 1. Has a long history with filecoin-project and has a lot of connections to teams across filecoin-project.  
+        #    She often has history or context on projects and can anticipate needs or issues that may arise.
+        - jennijuju
+        # Whey @rvagg?
+        # 1. He is an active in-the-GitHub-trenches maintainer for FilOz, often touching the 10+ repos that FilOz owns/maintains.
+        #    FilOz wants to ensure changes to these repos is done under code review and transparently,
+        #    and @rvagg is one of the key people who will be reviewing these changes.
+        #    (FilOz is also guinea-pigging this process, but the hope/intent is to have other groups manage their repos in this way too if its successful.
+        #    We are also dependent on some tooling improvement to support a diverse set of stakeholders that have limited blast radius.
+        #    See https://github.com/ipdxco/github-as-code/issues/126 for more info.)
+        # 2. He has experience working with github-mgmt in other contexts (e.g., ipld)
+        - rvagg
   infra:
     members:
       member: