doc: add missing reference to CARGO_PROFILE_<name>_STRIP in environ…

…ment variables docs

The doc for the env var was added in b6d1979 but was forgotten in env vars

src/doc/src/reference/environment-variables.md

@@ -123,6 +123,7 @@ In summary, the supported environment variables are:
 * `CARGO_PROFILE_<name>_PANIC` --- The panic strategy to use, see [`profile.<name>.panic`].
 * `CARGO_PROFILE_<name>_RPATH` --- The rpath linking option, see [`profile.<name>.rpath`].
 * `CARGO_PROFILE_<name>_SPLIT_DEBUGINFO` --- Controls debug file output behavior, see [`profile.<name>.split-debuginfo`].
+* `CARGO_PROFILE_<name>_STRIP` --- Controls stripping of symbols and/or debuginfos, see [`profile.<name>.strip`].
 * `CARGO_REGISTRIES_<name>_INDEX` --- URL of a registry index, see [`registries.<name>.index`].
 * `CARGO_REGISTRIES_<name>_TOKEN` --- Authentication token of a registry, see [`registries.<name>.token`].
 * `CARGO_REGISTRY_DEFAULT` --- Default registry for the `--registry` flag, see [`registry.default`].
@@ -185,6 +186,7 @@ In summary, the supported environment variables are:
 [`profile.<name>.panic`]: config.md#profilenamepanic
 [`profile.<name>.rpath`]: config.md#profilenamerpath
 [`profile.<name>.split-debuginfo`]: config.md#profilenamesplit-debuginfo
+[`profile.<name>.strip`]: config.md#profilenamestrip
 [`registries.<name>.index`]: config.md#registriesnameindex
 [`registries.<name>.token`]: config.md#registriesnametoken
 [`registry.default`]: config.md#registrydefault