Correct usage of 'sonarqube' with 'Sonarqube'

Also add 'Sonarqube' into vale vocab

Signed-off-by: Neemys <36508659+Neemys@users.noreply.github.com>

.changeset/forty-lobsters-guess.md

@@ -6,4 +6,4 @@
 
 The whole proxy's `'/sonarqube':` key can be removed from your configuration files.
 
-Then head to the sonarqube-backend plugin page to learn how to set-up the link to your sonarqube instances.
+Then head to the sonarqube-backend plugin page to learn how to set-up the link to your Sonarqube instances.

.changeset/ten-roses-walk.md

@@ -2,4 +2,4 @@
 '@backstage/plugin-sonarqube': patch
 ---
 
-Add ability to provide an optional sonarqube instance into the annotation in the `catalog-info.yaml` file
+Add ability to provide an optional Sonarqube instance into the annotation in the `catalog-info.yaml` file

.github/vale/Vocab/Backstage/accept.txt

@@ -283,6 +283,7 @@ shoutout
 siloed
 Sinon
 Snyk
+Sonarqube
 sourcemaps
 sparklines
 Splunk

plugins/sonarqube-backend/README.md

@@ -67,7 +67,7 @@ index 1942c36ad1..7fdc48ba24 100644
 
 ```
 
-This plugin must be provided with a `SonarqubeInfoProvider`, this is a strategy object for finding sonarqube instances in configuration and retrieving data from an instance.
+This plugin must be provided with a `SonarqubeInfoProvider`, this is a strategy object for finding Sonarqube instances in configuration and retrieving data from an instance.
 
 There is a standard one provided (`DefaultSonarqubeInfoProvider`), but the Integrator is free to build their own.
 
@@ -124,7 +124,7 @@ metadata:
     sonarqube.org/project-key: specialProject/YOUR_PROJECT_KEY
 ```
 
-If the `specialProject/` part is omitted (or replaced with `default/`), the sonarqube instance of name `default` will be used.
+If the `specialProject/` part is omitted (or replaced with `default/`), the Sonarqube instance of name `default` will be used.
 
 The following config is an equivalent (but less clear) version of the above: