Outer document
Byte 0-3: \x31\x00\x00\x00 - Length of the document 49 bytes (\x31 in hex)
Byte 4: \x04 - First element is an Array (type 4)
Byte 5-9: BSON \x00 - BSON e_name cstring (trailing null byte)
Inner document (Array)
Byte 10-13: \x26\x00\x00\x00 - Value for an array element is a document with index values keys
Byte 14: \x02 - First element of array is a String (type 2)
Byte 15-16: '0'\x00 - '0' e_name cstring for the first element
Value of key '0'
Byte 17-20: \x08\x00\x00\x00 - Length of the string
Byte 21-29: awesome\x00 - The null terminated string
Byte 30: \x01 - Second element of array is a double (type 1)
Byte 31-32: '1'\x00 - '1' ename cstring for the second element
...
In the area of concern we need \x02 (string type) followed by the e_name which is the character '0'.
Note: This is not octal 020. (even though it may look that way)
The \x02'0' bytes are then followed by the null byte to terminate the cstring in the e_name followed by the length of the string (8 bytes) which is awesome (7 bytes) and the null terminator for the string (1 byte). This leaves you with:
type[\x02] e_name['0'\x00] string[\x08awesome\x00]