docs: update managers in docs (#1320)

## Description

Closes: #XXXX
This PR updates the docs to update managers to core devs team.

<!-- Add a description of the changes that this PR introduces and the
files that
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---

### Author Checklist

*All items are required. Please add a note to the item if the item is
not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type
prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json)
in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR
Targeting](https://github.com/desmos-labs/desmos/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building
modules](https://docs.cosmos.network/v0.44/building-modules/intro.html)
- [ ] included the necessary unit and integration
[tests](https://github.com/desmos-labs/desmos/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go
code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable
and please add
your handle next to the items reviewed if you only reviewed selected
items.*

I have...

- [ ] confirmed the correct [type
prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json)
in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

.github/ISSUE_TEMPLATE/bug_report.md

@@ -3,7 +3,6 @@ name: Bug report
 about: Create a report to help us improve
 title: ''
 labels: 'kind/bug'
-assignees: 'RiccardoM'
 
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 <!-- < < < < < < < < < < < < < < < < < < < < < < < < < < < < < < < < < ☺ 

STABLE_RELEASES.md

@@ -137,4 +137,4 @@ Their responsibilities include:
 
 The Stable Release Managers are appointed by the Desmos Foundation. Currently residing Stable Release Managers:
 
-* @riccardom - Riccardo Montagnin
+* @desmos-labs/core-devs - Desmos-labs Core Dev Team