Allow appending table literals. (#2693)

docs/commands/append.md

@@ -1,21 +1,23 @@
 # append
 
-This command allows you to  append the given row to the table.
-
-**Note**:
-
-- `append` does not change a file itself. If you want to save your changes, you need to run the `save` command
-- if you want to add something containing a whitespace character, you need to put it in quotation marks
+Append a row to the table.
 
 ## Examples
 
-Let's add more cities to this table:
+Given the following text file `cities.txt` containing cities:
+
+```shell
+Canberra
+London
+Nairobi
+Washington
+```
+
+And getting back a Nu table:
 
 ```shell
 > open cities.txt | lines
 ───┬────────────
- # │
-───┼────────────
  0 │ Canberra
  1 │ London
  2 │ Nairobi
@@ -23,13 +25,11 @@ Let's add more cities to this table:
 ───┴────────────
 ```
 
-You can add a new row by using `append`:
+Add the city named `Beijing` like so:
 
 ```shell
 > open cities.txt | lines | append Beijing
 ───┬────────────
- # │
-───┼────────────
  0 │ Canberra
  1 │ London
  2 │ Nairobi
@@ -38,13 +38,11 @@ You can add a new row by using `append`:
 ───┴────────────
 ```
 
-It's not possible to add multiple rows at once, so you'll need to call `append` multiple times:
+It's not possible to add multiple rows at once, so you'll need to use `append` multiple times:
 
 ```shell
 > open cities.txt | lines | append Beijing | append "Buenos Aires"
 ───┬──────────────
- # │
-───┼──────────────
  0 │ Canberra
  1 │ London
  2 │ Nairobi
@@ -53,3 +51,55 @@ It's not possible to add multiple rows at once, so you'll need to call `append`
  5 │ Buenos Aires
 ───┴──────────────
 ```
+
+So far we have been working with a table without a column, which leaves us with plain rows. Let's `wrap` the plain rows into a column called `city` and save it as a json file called `cities.json`:
+
+Before we save, let's check how it looks after wrapping:
+
+```shell
+open cities.txt | lines | wrap city
+───┬────────────
+ # │ city
+───┼────────────
+ 0 │ Canberra
+ 1 │ London
+ 2 │ Nairobi
+ 3 │ Washington
+───┴────────────
+```
+
+And save:
+
+`> open cities.txt | lines | wrap city | save cities.json`
+
+Since we will be working with rows that have a column, appending like before won't quite give us back what we want:
+
+```shell
+> open cities.json | append Guayaquil
+───┬────────────
+ # │ city
+───┼────────────
+ 0 │ Canberra
+ 1 │ London
+ 2 │ Nairobi
+ 3 │ Washington
+───┴────────────
+───┬───────────
+ 4 │ Guayaquil
+───┴───────────
+```
+
+We append a row literal directly:
+
+```shell
+> open cities.json | append [[city]; [Guayaquil]]
+───┬────────────
+ # │ city
+───┼────────────
+ 0 │ Canberra
+ 1 │ London
+ 2 │ Nairobi
+ 3 │ Washington
+ 4 │ Guayaquil
+───┴────────────
+```