Fix/vale errors and warnings

[nick-vanpraet]

Description

Fixes #22

[nick-vanpraet]

{"message": "[Vale.Terms] Use 'DDEV' instead of 'ddev'.", "location": {"path": "docs/development-environment/how_to_install_with_ddev.rst", "range": {"start": {"line": 28, "column": 5}}}, "severity": "ERROR"}
  {"message": "[Vale.Spelling] Did you really mean 'Dev'?", "location": {"path": "docs/index.rst", "range": {"start": {"line": 5, "column": 167}}}, "severity": "ERROR"}
  {"message": "[Google.WordList] Use 'app' instead of 'application'.", "location": {"path": "docs/marketplace/allowlist_what_and_why.rst", "range": {"start": {"line": 12, "column": 61}}}, "severity": "WARNING"}
  {"message": "[Google.WordList] Use 'app' instead of 'application'.", "location": {"path": "docs/marketplace/allowlist_what_and_why.rst", "range": {"start": {"line": 19, "column": 60}}}, "severity": "WARNING"}
  {"message": "[Vale.Terms] Use 'PHP' instead of 'php'.", "location": {"path": "docs/components/translator.rst", "range": {"start": {"line": 31, "column": 173}}}, "severity": "ERROR"}
  {"message": "[Vale.Terms] Use 'OAuth2' instead of 'Oauth2'.", "location": {"path": "docs/components/integrations_authentication.rst", "range": {"start": {"line": [42](https://github.com/mautic/developer-documentation-new/actions/runs/7743362242/job/21114609229?pr=177#step:3:43)2, "column": 46}}}, "severity": "ERROR"}
  {"message": "[Vale.Terms] Use 'OAuth2' instead of 'Oauth2'.", "location": {"path": "docs/components/integrations_authentication.rst", "range": {"start": {"line": 429, "column": 19}}}, "severity": "ERROR"}
  {"message": "[Vale.Terms] Use 'Symfony' instead of 'symfony'.", "location": {"path": "docs/plugins/autowiring.rst", "range": {"start": {"line": 4, "column": [44](https://github.com/mautic/developer-documentation-new/actions/runs/7743362242/job/21114609229?pr=177#step:3:45)}}}, "severity": "ERROR"}
  {"message": "[Vale.Terms] Use 'Symfony' instead of 'symfony'.", "location": {"path": "docs/plugins/autowiring.rst", "range": {"start": {"line": 4, "column": 75}}}, "severity": "ERROR"}
  {"message": "[Vale.Terms] Use 'Codecov' instead of 'codecov'.", "location": {"path": "docs/plugins/continuous-integration.rst", "range": {"start": {"line": 8, "column": 10}}}, "severity": "ERROR"}

These still show up as errors/warnings but I feel like those aren't valid errors/warnings. Most are xrefs, which should be excluded according to Vale documentation (https://vale.sh/docs/topics/scoping/#restructuredtextv).

One is even between a vale off/on block and still shows up.

[RCheesley]

Thanks for this PR! A couple of things:

Here's our technical writing styleguide: https://contribute.mautic.org/education-team/technical-writing-styleguide.

We capitalise proper nouns, including the features of Mautic. This is to help people differentiate between when we're talking about a feature versus referring to something else - eg Email (the thing in Mautic) versus email management (in general).

Also we don't usually make changes for the Google styleguide core files (if they're updated in the future it will be overwritten) so I was interested in what the reasoning was there?

[RCheesley]

Thanks so much for all your work on this @nick-vanpraet!

LGTM 🚀