<replaceable> -> <emphasis>

Pandoc doesn't know <replaceable> so let's force it to be rendered as
italics.

doc/manual/src/command-ref/nix-hash.md

@@ -37,7 +37,7 @@ hash
 # Description
 
 The command `nix-hash` computes the cryptographic hash of the contents
-of each path and prints it on standard output. By default, it computes
+of each *path* and prints it on standard output. By default, it computes
 an MD5 hash, but other hash algorithms are available as well. The hash
 is printed in hexadecimal. To generate the same hash as
 `nix-prefetch-url` you have to specify multiple arguments, see below for
@@ -55,9 +55,9 @@ path | md5sum`.
 
   - `--flat`  
     Print the cryptographic hash of the contents of each regular file
-    path. That is, do not compute the hash over the dump of path. The
-    result is identical to that produced by the GNU commands `md5sum`
-    and `sha1sum`.
+    *path*. That is, do not compute the hash over the dump of *path*.
+    The result is identical to that produced by the GNU commands
+    `md5sum` and `sha1sum`.
 
   - `--base32`  
     Print the hash in a base-32 representation rather than hexadecimal.
@@ -67,17 +67,17 @@ path | md5sum`.
   - `--truncate`  
     Truncate hashes longer than 160 bits (such as SHA-256) to 160 bits.
 
-  - `--type` hashAlgo  
+  - `--type` *hashAlgo*  
     Use the specified cryptographic hash algorithm, which can be one of
     `md5`, `sha1`, and `sha256`.
 
   - `--to-base16`  
     Don’t hash anything, but convert the base-32 hash representation
-    hash to hexadecimal.
+    *hash* to hexadecimal.
 
   - `--to-base32`  
     Don’t hash anything, but convert the hexadecimal hash representation
-    hash to base-32.
+    *hash* to base-32.
 
 # Examples