Adjust levels of Vale rules

Backports #48850

Change the error levels of Vale style rules to pave the way for
requiring the Vale linter. Use the `warning` level for all rules except
for the step numbering rule. This mostly preserves the existing "check
prose style" GitHub Actions job behavior, in which Vale style rules are
optional. The one rule we require is to ensure that numbered `Step n/d`
headings follow the correct numbering scheme.

docs/vale-styles/3rd-party-products/aws-vs-amazon.yml

@@ -15,7 +15,6 @@
 #   /^AWS /{ print gensub(/AWS (.*)/,"  \"Amazon \\1\"","1") ": " $0}'
 extends: substitution
 message: "Incorrect AWS product name. Use %s instead of %s."
-scope: raw
 level: warning
 ignorecase: true
 swap:

docs/vale-styles/examples/teleport-accounts.yml

@@ -1,8 +1,8 @@
 extends: substitution
 message: "Incorrect example of a Teleport account URL. Use %s instead of %s."
-level: error
+scope: raw # So we can catch instances in code fences
+level: warning
 scope:
- - raw
 ignorecase: true
 swap:
   - 'https://(?!status|example)\w+.teleport\.sh': 'example.teleport.sh (or status.teleport.sh for the status page)'

docs/vale-styles/messaging/capitalization.yml

@@ -5,7 +5,7 @@ scope:
   - list
   - paragraph
 message: "Capitalize the names of Teleport services and features (%s is incorrect). See the Core Concepts page (https://goteleport.com/docs/core-concepts/) for a reference."
-level: error
+level: warning
 ignorecase: false
 tokens:
   # Allow for mentions of a local proxy service, but not "proxy service".

docs/vale-styles/messaging/consistent-terms.yml

@@ -7,7 +7,7 @@ scope:
   - list
   - paragraph
 message: For consistent product messaging in the docs, use '%s' instead of '%s'.
-level: error
+level: warning
 # Ignoring case because this rule is about word choice, rather than its
 # presentation/format.
 ignorecase: true

docs/vale-styles/messaging/protocol-products.yml

@@ -1,6 +1,6 @@
 extends: existence
 message: Avoid the impression that Teleport consists of multiple products for secure access, e.g., "Database Access" or "Server Access". Instead, talk about enrolling resources in your Teleport cluster, protecting resources with Teleport, or the ability for Teleport to proxy various protocols.
-level: error
+level: warning
 ignorecase: false
 tokens:
   - 'Server Access'

docs/vale-styles/structure/architecture-h2.yml

@@ -6,7 +6,7 @@
 # This style defines a how-to guide as any guide that includes at least one H2
 # beginning "Step [0-9]". 
 extends: script
-level: error
+level: warning
 message: "In a how-to guide, the first H2-level section must be called `## How it works`. Use this section to include 1-3 paragraphs that describe the high-level architecture of the setup shown in the guide, i.e., which infrastructure components are involved and how they communicate. If there is already architectural information in the guide, include it in a `## How it works` section."
 scope: raw
 script: |