DOCS-2997: Write the L2 network troubleshooting guide - #2949

[vale] reported by reviewdog 🐶 [Vale.Spelling] Did you really mean 'runtime's'? Raw Output: {"message":"[Vale.Spelling] Did you really mean 'runtime's'?","location":{"path":"calico-enterprise/networking/l2-bridge/troubleshoot.mdx","range":{"start":{"line":43,"column":79},"end":{"line":43,"column":88}}},"severity":"ERROR","code":{"value":"Vale.Spelling"}}