docs: Update name of v0-v1 flag

Follows open-policy-agent#7225

Signed-off-by: Charlie Egan <charlie@styra.com>

docs/content/v0-compatibility.md

@@ -27,8 +27,8 @@ to migrate their Rego to be compatible with OPA v1.0 using the below tooling opt
 
 1. The `rego.v1` import makes OPA apply all restrictions that are enforced by default in OPA v1.0.
    If a Rego module imports `rego.v1`, it means applicable `future.keywords` imports are implied. It is illegal to import both `rego.v1` and `future.keywords` in the same module.
-2. The `--rego-v1` flag on the `opa fmt` command will rewrite existing modules to use the `rego.v1` import instead of `future.keywords` imports.
-3. The `--rego-v1` flag on the `opa check` command will check that either the `rego.v1` import or applicable `future.keywords` imports are present if any of the `in`, `every`, `if` and `contains` keywords are used in a module.
+2. The `--v0-v1` flag on the `opa fmt` command will rewrite existing modules to use the `rego.v1` import instead of `future.keywords` imports.
+3. The `--v0-v1` flag on the `opa check` command will check that either the `rego.v1` import or applicable `future.keywords` imports are present if any of the `in`, `every`, `if` and `contains` keywords are used in a module.
 
 ### v0.x compatibility mode in the OPA binary
 
@@ -42,18 +42,16 @@ releases:
 - `eval`: supports Rego v0.x syntax modules, use of `import rego.v1` is optional.
 - `exec`: supports Rego v0.x syntax modules, use of `import rego.v1` is optional.
 - `fmt`*: formats modules to be compatible with OPA v0.x syntax. See note about
-  `--rego-v1` flag below.
+  `--v0-v1` flag below.
 - `inspect`: supports Rego v0.x syntax modules, use of `import rego.v1` is optional.
 - `parse`: supports Rego v0.x syntax modules, use of `import rego.v1` is optional.
 - `run`: supports modules (including discovery bundle) using Rego v0.x syntax, use of `import rego.v1` is optional. Binds server listeners to all interfaces by default, rather than localhost.
 - `test`: supports Rego v0.x syntax modules, use of `import rego.v1` is optional.
 
-Note (*): the `check` and `fmt` commands also support the `--rego-v1` flag,
+Note (*): the `check` and `fmt` commands also support the `--v0-v1` flag,
 which will check/format Rego modules as if compatible with the Rego syntax of
 _both_ the old 0.x OPA version and current OPA v1.0.
 
-Note (*): the `--rego-v1` flag is not supported before OPA `v0.59.0`.
-
 Note (*): Pre v1.0 versions of OPA also support a comparable `--v1-compatible`
 flag which can be used to produce and consume Rego v1 bundles. See
 [Upgrading to v1.0](./v0-upgrade) for more information on how to use this flag

docs/content/v0-upgrade.md

@@ -455,12 +455,14 @@ upgrade their Rego code to conform to best practices, and to be compatible with
 OPA v1.0. These steps are largely based on the process outlined in this
 [detailed blog post](https://www.styra.com/blog/renovating-rego/).
 
-1. `opa check`, this will catch any parse or compilation errors.
-2. `opa check --strict`, this will raise a number of other issues found in code
+Before starting the upgrade, users are recommended to ensure they have a local
+OPA binary of version 1.0 or later.
+
+1. `opa check --v0-v1`, this will catch any parse or compilation errors.
+2. `opa check --v0-v1 --strict`, this will raise a number of other issues found in code
    that might make it incompatible with OPA v1.0 such as the use of deprecated
    built-ins or duplicate imports.
-3. Automatically reformat your code for OPA v1.0 with
-   `opa fmt --write --rego-v1`.
+3. Automatically reformat your code for OPA v1.0 with `opa fmt --write --v0-v1`.
 4. `regal lint`, the [Regal linter](/integrations/regal/) has many more rules to
    test for issues in Rego code that can lead to errors, poor performance or
    unexpected behaviour.