Update rule and list of automatically fixable rules in docs

Signed-off-by: Sean Ledford <s_ledford@apple.com>

Author: SeanLedford

docs/fixing.md

@@ -22,6 +22,7 @@ Currently, the following rules are automatically fixable:
 - [use-assignment-operator](https://www.openpolicyagent.org/projects/regal/rules/style/use-assignment-operator)
 - [no-whitespace-comment](https://www.openpolicyagent.org/projects/regal/rules/style/no-whitespace-comment)
 - [directory-package-mismatch](https://www.openpolicyagent.org/projects/regal/rules/idiomatic/directory-package-mismatch)
+- [prefer-equals-comparison](https://www.openpolicyagent.org/projects/regal/rules/idiomatic/prefer-equals-comparison)
 - [use-rego-v1](https://www.openpolicyagent.org/projects/regal/rules/imports/use-rego-v1) (v0 Rego only)
 
 So, how do you go on about automatically fixing reported violations?

docs/rules/idiomatic/prefer-equals-comparison.md

@@ -4,6 +4,8 @@
 
 **Category**: Idiomatic
 
+**Automatically fixable**: [Yes](/regal/fixing)
+
 **Avoid**
 ```rego
 package policy

pkg/fixer/fixes/preferequalscomparison.go

@@ -30,7 +30,7 @@ func (p *PreferEqualsComparison) Fix(fc *FixCandidate, opts *RuntimeOptions) ([]
 			continue
 		}
 
-		lines[loc.Row-1] = line[0:loc.Column-1] + "=" + line[loc.Column-1:]
+		lines[loc.Row-1] = line[0:loc.Column] + "=" + line[loc.Column:]
 		fixed = true
 	}