add documentation file for first command

docs/commands/first.md

@@ -0,0 +1,28 @@
+# first
+
+Use `first` to retrieve the first "n" rows of a table. `first` has a required amount parameter that indicates how many rows you would like returned. If more than one row is returned, an index column will be included showing the row number.
+
+## Examples
+
+```shell
+> ps | first 1
+━━━━━━━┯━━━━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━
+ pid   │ name         │ status  │ cpu
+───────┼──────────────┼─────────┼───────────────────
+ 60358 │ nu_plugin_ps │ Running │ 5.399802999999999
+━━━━━━━┷━━━━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━
+```
+
+```shell
+> ps | first 5
+━━━┯━━━━━━━┯━━━━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━
+ # │ pid   │ name         │ status  │ cpu
+───┼───────┼──────────────┼─────────┼───────────────────
+ 0 │ 60754 │ nu_plugin_ps │ Running │ 4.024156000000000
+ 1 │ 60107 │ quicklookd   │ Running │ 0.000000000000000
+ 2 │ 59356 │ nu           │ Running │ 0.000000000000000
+ 3 │ 59216 │ zsh          │ Running │ 0.000000000000000
+ 4 │ 59162 │ vim          │ Running │ 0.000000000000000
+━━━┷━━━━━━━┷━━━━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━
+```
+