use separate paragraphs inside list items

doc/manual/src/command-ref/nix-env/upgrade.md

@@ -28,36 +28,42 @@ version is installed.
 
 # Flags
 
-  - `--lt`\
+  - `--lt`
+
     Only upgrade a derivation to newer versions. This is the default.
 
-  - `--leq`\
+  - `--leq`
+
     In addition to upgrading to newer versions, also “upgrade” to
     derivations that have the same version. Version are not a unique
     identification of a derivation, so there may be many derivations
     that have the same version. This flag may be useful to force
     “synchronisation” between the installed and available derivations.
 
-  - `--eq`\
+  - `--eq`
+
     *Only* “upgrade” to derivations that have the same version. This may
     not seem very useful, but it actually is, e.g., when there is a new
     release of Nixpkgs and you want to replace installed applications
     with the same versions built against newer dependencies (to reduce
     the number of dependencies floating around on your system).
 
-  - `--always`\
+  - `--always`
+
     In addition to upgrading to newer versions, also “upgrade” to
     derivations that have the same or a lower version. I.e., derivations
     may actually be downgraded depending on what is available in the
     active Nix expression.
 
-  - `--prebuilt-only` / `-b`\
+  - `--prebuilt-only` / `-b`
+
     Use only derivations for which a substitute is registered, i.e.,
     there is a pre-built binary available that can be downloaded in lieu
     of building the derivation. Thus, no packages will be built from
     source.
 
-  - `--preserve-installed` / `-P`\
+  - `--preserve-installed` / `-P`
+
     Do not remove derivations with a name matching one of the
     derivations being installed. Usually, trying to have two versions of
     the same package installed in the same generation of a profile will