use separate paragraphs inside list items

doc/manual/src/command-ref/nix-env/opt-common.md

@@ -2,7 +2,8 @@
 
 The following options are allowed for all `nix-env` operations, but may not always have an effect.
 
-  - `--file` / `-f` *path*\
+  - `--file` / `-f` *path*
+
     Specifies the Nix expression (designated below as the *active Nix
     expression*) used by the `--install`, `--upgrade`, and `--query
     --available` operations to obtain derivations. The default is
@@ -13,13 +14,15 @@ The following options are allowed for all `nix-env` operations, but may not alwa
     unpacked to a temporary location. The tarball must include a single
     top-level directory containing at least a file named `default.nix`.
 
-  - `--profile` / `-p` *path*\
+  - `--profile` / `-p` *path*
+
     Specifies the profile to be used by those operations that operate on
     a profile (designated below as the *active profile*). A profile is a
     sequence of user environments called *generations*, one of which is
     the *current generation*.
 
-  - `--dry-run`\
+  - `--dry-run`
+
     For the `--install`, `--upgrade`, `--uninstall`,
     `--switch-generation`, `--delete-generations` and `--rollback`
     operations, this flag will cause `nix-env` to print what *would* be
@@ -29,7 +32,8 @@ The following options are allowed for all `nix-env` operations, but may not alwa
     [substituted](@docroot@/glossary.md) (i.e., downloaded) and which paths
     will be built from source (because no substitute is available).
 
-  - `--system-filter` *system*\
+  - `--system-filter` *system*
+
     By default, operations such as `--query
                     --available` show derivations matching any platform. This option
     allows you to use derivations for the specified platform *system*.