Docs: Update the minimum version of go from 1.17 to 1.18 (#6101)

* Docs: Update the minimum version of go from 1.17 to 1.18

The version of go has been bumped, but the docs haven't been updated.  The commit updates the developer guide with the correct version.

Signed-off-by: David Lanouette <[email protected]>

Author: davidlanouette

changelog/fragments/docs-bump-go-version.yaml

@@ -0,0 +1,14 @@
+entries:
+  - description: >
+      (docs) Update the go version in the developer guide.  The documentation wasn't updated when the go version was bumped to v1.18.
+
+    # kind is one of:
+    # - addition
+    # - change
+    # - deprecation
+    # - removal
+    # - bugfix
+    kind: "bugfix"
+
+    # Is this a breaking change?
+    breaking: false

website/content/en/docs/contribution-guidelines/developer-guide.md

@@ -9,7 +9,7 @@ weight: 1
 ### Prerequisites
 
 - [git][git-tool]
-- [go][go-tool] version 1.17
+- [go][go-tool] version 1.18
 
 ### Download Operator SDK